Mercedes S-class (W221) 2006-2013


Some say it’s a bargain. Some say it’s a money pit. And some say it’s a nightmare which you should not purchase out of warranty. But sometimes it’s just hard to not buy a car like this – or just not to think of buying this thing.

This thing – the S class. High ranking politicians had one of these, various country leaders had one of these, dictators? Yes, they also often have one of these: very interesting

But it’s also a car which always brings new technologies to the automotive industry and it’s also a car, which should look great even after 15 or 20 years after the first model was produced. But let’s be honest, while the predecessor of this S class-the W220 had plenty of new tech, it was also spiced with bigger cost reduction measures which caused numerous reliability and rust issues + the design of this W220, say what you want, it really doesn’t aged very well. Mainly the front of the car of the before facelift versions looks really outdated at this day and age ↓ ↓ ↓

However look at the W221! The exterior of this car not only looks great even today, but it’s also more interesting than the exterior of the newest W222 S class! And the cost reduction with the new tech? Well, it seems like at this time Mercedes woke up, cut most of the cost reduction to an optimal level and fixed numerous things which were not acceptable in the predecessor. But while they fixed plenty of things they also unintentionally (or intentionally?) did a couple of bigger mistakes…

There is an awesome quote in the brochure of this car, there is something like: We give the best for people who expect the best.

Ok, but if the engine mounts made from chocolate, the balance shaft made from potatoes and the gearbox made from carrots are counting as the best, then there is a problem in the Matrix – somewhere.

But let’s not overtake the things which should not be overtaken and let me finish the damn intro with something like:

This is a VERY COMPLEX car and you have to understand that the complexity comes with risk but also with rewards. Is it ok?



The interior of this Mercedes can be equipped with almost everything you can imagine so it’s easier to mention the things it can’t have:

There is no:

  • touch screen
  • wireless phone charger
  • Bluetooth audio streaming
  • Android auto or Apple car play compatibility
  • USB port
  • heated or cooled cup holders
  • aaand I don’t know what more is missing, if you know about something else then you can write it in the comments!

But let’s be honest, most of these things are not there because of the age of the car, so that’s nothing unusual.

There is:

  • wide comfortable and supportive front electrically adjustable massage seats which do have numerous individual air cushions in them
  • heated and ventilated front and rear seats
  • night vision system
  • noise insulating infrared-reflecting double glazing
  • 2 part sunroof
  • Pre-Safe safety system-which makes crashing into stuff more comfortable
  • complex automatic AC
  • and I could continue like forever…

+ Obviously let’s not forget that the rear passengers can have almost every comfort feature in the back as well, including power sunshades in doors and on back window, fridge, separate screens with controls and so on...

Some of this stuff was optional, some of it standard on specific models.

By the way when it comes to music, there is no genuine AUX socket anywhere (but it can be retrofitted). Instead, there is only a slot for SD cards under the front AC control panel- behind a small cover.

On early cars this slot is bigger than a regular SD card, so you will need a PCMCIA adaptor → in which you can put the regular SD card → then put all this in the slot → and just then play the damn music finally. On facelifted cars on the other hand, the slot is a regular SD card slot so in this case you don’t need the adaptor.

Materials, build quality

Soft touch coating

All the used materials are high quality and pretty durable, except the soft touch coating of the buttons on the steering wheel and on the glove box opening button. On the before facelift cars this coating becomes worn and sticky and it will look horrible. But there is no need to panic, since you can remove this top sticky layer by cleaning these buttons properly. Just don’t clean them with some aggressive alcohol cleaner because you will remove the main layer too!

how to fix the sticky buttons

Loose leather

Then there are many cases of more or less loose/wrinkled leather usually on the front armrest, but occasionally also on the door panel armrest + on the before facelift cars the front driver’s seat base leather can be more often loose too (but this also depends on the drivers weight and the mileage of course).

how to fix the loose leather on armrest + how to remove it

how to fix the loose leather on seat and armrest

Build quality

The interior build quality is very good, so again a big step forward compared to the predecessor. But nothing is perfect, so numerous owners complained about creaking/squeaking or buzzing sounds from the front door panels – especially from the wood trim area. This sound can be caused by the plastic LED ambient lighting strip – behind the wood trim, which can become loose. But the sound can be caused by the door panel itself too – which is making contact with the metallic part of the door. In both cases you can put felt tape on contact points to eliminate the noises.

some more information about this door panel noise here and here

video – how to fix the door panel noise

The interior of the V12 models does have a more premium feel compared to the other standard versions. This is because all the surfaces are covered in leather instead of the standard plastic finish of the various parts – in the less equipped models.

Body, paintjob, rust protection

Luckily unlike the predecessor, this S class is not famous for rust issues. And it seems like Mercedes wanted to be really sure that it won’t rust that much, so the hood, front fenders, doors and the trunk lid are made from aluminum. And of course the rust protection of the remaining parts of the body is also very good.

However, if you are using the car on winter salty roads then it’s good to clean the rear wheel arches from inside and put some wax there – this part is from steel and is a bit more prone to rusting.

Possible problems

1. Optional front dynamic multicontour seats

I will start with the optional front dynamic multicontour seats which are like really, really complex. And the complex things can obviously break. So leaking air bladders are not uncommon, occasionally the electronic modules can be faulty-or they will only need a software update, and sometimes even the seat wiring can be damaged.

some info on how to fix seat wiring

To fix for example the leaking air bladders you either buy a complete air bladder assembly, or you can use some flexible vinyl adhesive on the leaking spots which will fix the leaks. For how long will the glue lasts? Well who knows? But you can try it. Just keep in mind that either way you will have to disassemble certain parts of the seat. If you can’t do it yourself then keep approx. 900 € which is the approximate price for replacing the seat air bladder assembly.

how to fix leaking seat air bladder video

All in all, it’s really important to check all the adjustments of these seats. Check the lumbar support, and if the car is equipped with the dynamic multicontour seats then check if all the bladders are inflating and deflating without any issues, check the massage feature and try to adjust the side bolsters. But actually the easiest is to test the bladders via the original diagnostic software (Star diagnostic program), which will tell you if the bladders are holding the air without leaks and it will show you the fault codes from these seats as well.

Obviously, the seats can be also heated and ventilated so test these features too. But focus mainly on the seat heating – it can be more often faulty, and it costs up to $1 200/seat to fix it.

The dynamic seat feature is pretty awesome since if you are cornering, then the dynamic seat will inflate the particular bolster on the seat to give you maximal support in the seat.

2. Amplifier

-There are many cases of dead amplifier = in this case there will be no sound from the multimedia system or the sound will occasionally cut off and eventually you won’t see the radio stations either.

3. AC system

-The AC system can have a couple of issues too. First of all the blower motor itself can fail completely, or occasionally it will cut off, and eventually it will just make a strange squeaking sound at low speed. The motor wears out over time and collects dirt on the brushes so this is nothing extraordinary. But luckily the motor is located in the passenger footwell area under the glove box – it’s held by 5 screws so it’s not hard to replace it. But before replacing it, first you can try to clean it with compressed air which can occasionally bring it back from the dead. But if your motor still works, then you will extend the lifetime of it by cleaning it. how to remove the blower motor video

Over time a decent amount of dirt and black carbon ash from the electronic brushes will accumulate in the motor assembly causing it to spin harder-so clean it and put some oil on the bearings of the shaft.

However sometimes the blower regulator/resistor which is next to the motor can fail, causing the motor to occasionally cut off, eventually it will not blow the air very strong-even if its adjusted to full speed + you also get a fault code for this regulator: 951D A32n1 blower regulator/resistor fault code

By the way, if your car is equipped with the 4 zone AC then the rear blower motor regulator can fail too causing the same issue as the front. On the other side the rear motor itself is usually ok.

After you checked the damn blower motor, you should also check the AC temperature settings since the front heater valve which is located under the windshield wipers can fail causing only cold air to blow from the front vents.

how to replace front change over valve

how to replace the front change over valve video

But this is not the only valve which can fail, because if you have 4-zone AC then the valve which controls the rear AC temperature can fail too. However in this case the situation will be the exact opposite of the front valve failure, which means that only hot air will blow from the center rear vents even if the temperature is set to the coldest settings – In other words in summer you can set up a sauna in the rear, and if you turn off the rear AC then you can use the center console storage area as an oven since your center console becomes really hot anyway.

4. Washer fluid leaks

-Then there are more often cases of leaking windshield washer fluid, mostly because of the rubber grommets seated in the tank which will over time not seal properly, or because of a hose. Occasionally the headlight washer assembly can leak as well-in this case there will be a puddle directly below the headlights usually in cold weather + don’t forget to test the windshield washers before buying because the 2 washer motors mounted on the washer tank can break too.

detailed info on windshield washer reservoir and motor

how to remove the bumper video – to fix the leaking headlight washers

5. Sunroof motor

-This Mercedes can be equipped with the regular or with the panoramic sunroof. Either way try to open and close the sunroof a couple of times since the sunroof can get stuck because of the skipping motor. This sunroof motor will have play due to the rubber mounts on the mounting screws of this motor, so it gets loose and it will make a loud clicking/rattling skipping noise. If the gear on the motor is not worn then you can fix this issue pretty easily for free by adding washers to the mounting screws.

how does the bad sunroof mechanism sound like and how to manually close the sunroof if its stuck video

how to fix the skipping sunroof motor for free video

how to remove the headliner to access the sunroof motor

“to extend the lifetime of the sunroof mechanism occasionally clean and put grease on the moving parts”


You have to keep in mind that this is not just some kind of an average car, so there is a huge amount of wiring, switches, fuses, relays, modules and other magical electronic boxes which controls God knows what. However generally speaking – the various electronic issues can occur mostly on the before facelift cars – but I have to add that they are not that common as you would think. Either way, to minimize these problems keep the battery, the alternator + the batteries in a very good condition!

This Mercedes can be equipped with 1 or 2 main batteries. The first battery is always located under the hood – on a regular visible place. But if the car is equipped with 2 batteries then the second is located in the trunk-behind the trunk rear carpet panel. And actually there is also a 3rd smaller auxiliary battery under the driver’s side dash which can be weak too. All in all, just make sure that all of these batteries are in good condition, because if one of them is weak then you can get various electronic glitches, warnings or you won’t be able start the car. how to replace the small auxiliary battery video

“if you have plenty of free time then you can look at this thread for more information about the batteries”

“and if you got even more of free time then you can read thru the owners manual of this Mercedes here

-Then there is alternator which is not famous for premature failure, although it can be of course more often worn because of the bigger load it has to bear. On the other side there are more cases of faulty voltage regulator behind the alternator which will cause voltage fluctuation, and that’s not good. It’s not good because the voltage fluctuations/undervoltage will cause various electronic issues, and some say that this is the main cause of issues with the ISM for example!

And what is ISM?

ISM is the electronic gearbox selector module which can fail mainly on the before facelift cars – causing a situation in which you won’t be able to shift between the basic gears-PRND. There is no mechanical connection between the gearbox and the gear selector, so if the ISM gets stuck in Drive and the engine is off – then you won’t be able to start the engine. This magical ISM module is mounted on the side of the gearbox which means, that you will have to raise the car to access it. But actually, in some cases it’s enough to recalibrate this module using a diagnostic computer to make it work! However, if you will need to replace it then be prepared that this is not a plug and play procedure, so this part has to be programmed specifically to your car!

Other stuff

Moving on, there are also cases when you have various electrical issues at the same time like: not working or intermittently working windshield wipers, not working AC, not working power windows, power seats and so on. Well, in this case there is a very high chance that the fuse module under the hood will be faulty. This module contains fuses-which can fail, relays-which can fail, metallic plates-which can cause issues, and there is also the SAM module next to it-which can fail too.

You can’t start the car but the batteries, fuses and the SAM modules are ok? In this case you have most probably a bad starter motor.

However listen, as I said the various major electronic issues are not extremely common so there is no need to start to panic yet. So if:

  • your battery + alternator are in good condition
  • the water has not leaked into these magical electronic things
  • the wiring is not damaged
  • and if nobody has spilled some drinks onto the interior switches

then all these things are usually working in peace in the background. On the other side, because of the big amount of electronic features you really should take your time and inspect everything before buying.

And of course I have to mention the regular stuff which can break too like the: window regulators, the well-known keyless entry door handles, electronic parking brake or door locks – so additionally don’t forget to check these things.

Water leaks into the interior

As the other cars, this S class can also have issues with water leaks into the interior so as always don’t forget to check carefully for traces of water in the footwell area and on the headliner!

There are 2 main causes of these leaks:

1. water drains under the windshield

-First, there are the water drains under the windshield. Two drains are under the hinges and 2 drains are in the middle, but mostly the side drains and the first middle drain can clog over time causing the water to overflow over the plastic scuttle panel. This is not exactly good since the battery, the interior air intake and also the fuse box with the SAM electronic module are in this area. The water can reach all these things and of course it can leak into the interior. And by the way you should inspect specifically the air intake itself with a flashlight as well, since there is an additional drain at the bottom of this air intake. This drain is a rubber grommet which can clog – causing the water to accumulate here and leak into the blower motor and into the interior.

Next there is another similar rubber grommet, but this time on the lower part of the hood which drains the water into the second middle drain so make sure that this grommet is clean too.

But lets go back to the damn side drains under the hood hinges which are ending behind the wheel arch liners. The water will leak first in a collector on the inside of the liner, and just after this – out of the drain hole in the liner. The drain hole in the liner is too small (as you can see on the picture below) so it will clog with all the rubbish. Long story short, to properly clean the side drains you should partly remove the wheel well liners-to clean the drain itself and clean the rubbish in the liner collector as well.

2. sunroof drains

-Lastly there are the sunroof drains which can clog. There are 4 drains on the regular sunroof, but if you don’t want to remove the headliner then you will be able to access only the front drains, so use some fish tape or edge trimmer line to carefully clean these drains. The panoramic sunroof on the other hand doesn’t have any drains – at least it looks like there are none, but if I’m wrong about this then correct me in the comments.


Suspension types of this S-class:

Airmatic adaptive air suspension (standard)

Active ABC hydraulic suspension (standard for S600 and for all the AMG versions, optional for S450, S500, S550, S420 CDI, S450 CDI)


-This is a regular self leveling air suspension which is obviously comfortable, but you can adjust it from comfort to a bit stiffer sport mode as well, and you can raise the car a little with a button on the dash.

“In the before facelift cars you can put the suspension from comfort to sport mode only with the button on the center console, which means that in this case the sport mode of the suspension will be activated only with the sport mode of the gearbox at the same time. On the other side in the newer facelifted cars you can adjust the suspension to sport mode by pushing the sport button on the dash which means that in these newer cars you can adjust the suspension and the gearbox characteristics separately”

It’s all great and awesome, but there are the well-known air suspension parts which will sooner or later break, so: mainly the air compressor can more often wear out, the air struts can start to leak anytime basically-although still mostly on the before facelift cars, and rarely one of the air pipes can crack a little and leak. All of this means that you should definitely keep extra money to replace at least half of these parts. However replacing the air struts or the air compressor is actually not hard at all, and while the genuine parts are obviously expensive, there are also refurbished or new aftermarket struts and air compressors available for a much lower price + there are the very cheap air compressor repair kits available too.

Before buying:

  • It’s good to test the air suspension by at least raising and lowering the car a couple of times
  • Make sure the car is raising at a noticeable speed and the compressor is not very noisy! (the air compressor is located behind the front fender on the right side)
  • Check if the car is standing in level
  • Inspect the struts visually for damage
  • And keep in mind that the suspension should not lower even after a week of sitting!


-But let’s move on to the ABC active hydraulic suspension which is also comfortable, adjustable and self leveling. To top of that, compared to the airmatic it significantly reduces the body roll in all situations. So while the adaptive air suspension slowly adapts to the various situations, the active hydraulic suspension very quickly actively adapts to the situations-it actually adapts 5 times/second they say!

All the AMG and V12 models are STANDARDLY equipped with this ABC suspension.

And again, it’s all great and awesome but the maintenance and repair costs of this suspension are higher than in cars with the conventional airmatic setup. Although I have to add that this ABC suspension is more reliable than in the previous generation of this S class, and it can actually withstand more than 200 000 km without issues – but this of course doesn’t mean that there are no weak points.

Instead of air, this ABC suspension uses hydraulic fluid which is under high pressure. The fluid is distributed by numerous lines thru the valve blocks into the accumulators and shocks. The pressure is maintained by a main pump which is mounted on the front of the engine.

And this pump can be faulty. So if you hear various whining, howling or grumbling noises (turbine like, turbocharger like sounds) from the pump and you feel a vibration in the interior and especially in the steering wheel at idle-up to approximately 2000 RPM, then most probably the pulsation dampener mounted on this pump is faulty. The pulsation dampener is there to even out the vibrations in the fluid from the pump, so that’s why when it fails you get the already mentioned symptoms. The good thing is, that this part itself is not that expensive, however in cars equipped with the V8 engines there is very little space around the pulsation dampener, so it’s harder to replace it, which means that you have to: release the engine mount-remove the whole pump-and just then replace the pulsation dampener itself. On the other side the paradox is that in cars with the V12 engines the pulsation damper can be replaced easily without removing the whole pump!

Interestingly, sometimes the expensive pump itself can be worn as well. But you have to remember that not only the ABC pump but also the power steering pump is combined in this single unit, so it is complex and expensive. However you can have it refurbished for a much lower price, or you can buy a used pump if you like to gamble.

Then there are the lines which can crack/burst and leak, and not only because of the age or faith, but also because of the road salt which will cause corrosion on them. So before buying check not only for the already mentioned pump noises but also for leaks from these pipes, and especially check the lines in in front of the engine since one of them can burst more often and dump all the fluid out.

“Keep in mind that if one of the oil line bursts and your pump will run on low or no fluid at all – even for a very short time, then there is a very high chance that the pump gets permanently damaged and it starts to make the already mentioned noises!”

On the other side not only the pipes, but also the shock absorbers themselves can start to leak. However I have to add that this is not like extremely common and mostly still just the before facelift cars are affected because of the age. But if the shock is just misting oil then there is no need to panic, just check the fluid level regularly (the misting can actually remain the same for a couple of years without getting worse, so you can leave it like this with no worries – just occasionally check it if its not getting worse). However if it starts to visibly drip oil and you can see that the oil level is slowly decreasing then you should replace the shock in the near future! Nevertheless, be mentally prepared that one brand new ABC shock absorber costs approximately the same as the new pump, although again because of the high price there are also remanufactured shocks available which are cheaper. + if you have like really bad quality roads in your country then be prepared that the strut in these shocks can break-there are already some cases of this (yes there is a regular strut in these special struts, and if the strut breaks then the car will handle like garbage, obviously)

Issues with the stiffness of this ABC suspension can occur too, which means that in some corner the shock will be stiff while the others remain soft/comfortable, or the whole suspension becomes stiff-this can be caused by faulty acceleration sensors on before facelift cars

stiff ABC suspension on before facelift cars can be caused by faulty acceleration sensors more info here

To minimize issues with the various components of this complex suspension and to extend its lifetime – you should definitely replace the hydraulic fluid and filter in this system every 4 years or 60 000 km and check the fluid level regularly. By the way if you want to replace the ABC filter then keep in mind that you can’t order it for the w221 separately. However the filter is identical with the W220 models which can be actually ordered separately, so just order the filter for the W220 models and put it in your W221.

how to replace ABC fluid video , the tool to flush the system

To finally end the issues list, both of the suspensions do have height sensors which are usually ok, just the leveling arms attached to them can seize up or pop out over time causing suspension related fault codes or the car will stand unevenly. So check those damn height sensors dude!

Cars equipped with the Airmatic do have a visible air line on top of the front shocks and cars equipped with the ABC don’t have anything on this place, so if you are looking for an S class then you can quickly and easily check which suspension the car has.

The other suspension components: control arm bushings, ball joints, tie rods so all that usual shit can fail before 100 000 mi – so be prepared to replace this stuff before this mileage point and check for all those usual noises from the suspension.

“A creaking sounds from the front can be from the front sway bar bushings”

Petrol engines

The petrol engines are definitely not unreliable but there are a couple of weak and weaker points.

Let’s start with something minor and not that expensive to fix. Engine mounts! The engine mounts in these cars are made from chocolate so they can easily compress, or fall apart completely even before 70 000 mi. In this case you get vibrations at idle or at acceleration, and also while in gear standing on the brake pedal. By the way the transmission mount can fail prematurely as well so keep extra money to replace it too.

ruined engine mounts video example

replacing the engine mounts on a S500/S550 can cost up to $3 000 at the dealer, but approx. $600 at an independent mechanic

V6 and V8 to 2010 (M272, M273)

balance shaft sprocket failure

-The well known balance shaft sprocket failure can occur in cars made to 2007. Mostly the V6 M272 engines are affected but the V8 M273 engines can have occasionally worn gears as well. Because of the worn gear the timing chain gets loose which will cause misfires, an illuminated check engine light with stored fault codes, eventually a rattling noise from the engine and at the end the chain will skip which will most probably destroy the engine.

Replacing the faulty parts is not cheap mainly because the engine has to be removed, so all in all it’s simply better to avoid the cars made to 2007 and buy a car made from 2008 which has the updated gear. However some cars made in late 2007 can have the updated parts fitted as well so if you found a car from this time period then you should check the engine serial number if it’s in the affected range or not. But of course if the previous owner replaced the sprocket and the timing chain then you can buy an earlier car.

website for checking the balance shaft issue affected range of engines

variable intake manifold

-The next problem which affects all the V6 M272 and V8 M273 engines is related to the complex variable intake manifold. Basically a plastic arm on the outside can break or sometimes the plastic flaps inside the intake manifold can fall apart as well causing: misfires, loss of power and eventually an illuminated check engine light. The broken outside plastic arm can be fixed by replacing it with an improved metallic one, however in this case it’s also good to remove and clean the intake manifold itself, because there will be most probably a bigger or smaller amount of carbon deposit in it.

On the other side the simplest and fastest solution is to buy a new complete intake manifold- since after replacing the outside arm only and cleaning the intake manifold, the inside plastic flaps in it can still break.

Improved metallic outside arm with new gaskets – 110 € / $125

New complete intake manifold – from 500 € / $566 (replacing it at the dealer – 2 200 € / $2 500)

camshaft adjustment solenoids

-Then there are 4 cam adjustment solenoids which can leak oil or they can also fail, again on the already mentioned M272 and M273 engines. If they start to fail then you will experience various symptoms like: an illuminated check engine light, stored fault codes or even loss of power, poor idle/misfires, eventually stalling.

The solenoids are located on the front of the engine so replacing them is not very hard and luckily they are also not expensive. how to replace these solenoids

+ more info of other sensors which can fail on these engines

how to replace the spark plugs S550 V8 2006-2011

V6 and V8 to 2010 bonus issue (M272, M273)

Before I continue with the newer engines, I have to mention the cases of worn cylinder walls in these M272 and M273 engines. Listen, this issue is NOT very common so don’t panic. However if:

  • the previous owner used incorrect oil
  • it is a higher mileage car with too long oil change interval
  • if the engine has a long lasting issue with leaking fuel injectors
  • or if the engine has a long lasting issue with vacuum leaks-which lead to incorrect detonation thus increasing the temperature in the combustion chamber

THEN yes, the engine can have worn cylinder walls causing oil consumption, misfires, loss of compression, knocking noise, and destroyed engine.

V6 and V8 from 2011 (M276, M278)

Next there are the newer versions of these engines. The V6 M276 remained without a turbocharger, while the M278 V8 got 2 turbochargers. This translates to 435 hp and 700 NM of torque which is more than enough. Interestingly the turbochargers in this V8 are usually reliable, unless of course the car was abused, used only on short distances or it has high mileage. + Rarely a rod above the turbo can break causing loss of power and the 0299-turbo under boost – fault code.

this engine has to be removed from the car to replace the turbochargers, so be prepared to pay thousands, thousands and thousands when they fail: approx. $9 000 in total to replace 1 turbocharger and remove engine

So the turbochargers are usually ok, however what is not really ok is, that these 2 engines can develop a short rattling noise at cold start which is caused by the loose timing chain tensioners. Because of this the chain can stretch prematurely which is not good. So, to fix this you have to replace the tensioners and additionally fit a small check valve into the cylinder head oil supply bore-directly behind the tensioner.

But if the rattle persists then you should replace also the camshaft adjusters which can be faulty, and this step should finally solve the rattle!

This is how the engine should sound during startup – start up video without rattle

Also keep in mind that these newer engines are equipped with direct injection so generally speaking there should be a higher chance of faulty injectors or carbon build up. But in this case there are not many issues with the injectors and the carbon build up on the intake valves is usually not major either. This of course doesn’t mean that there is none of these issues so it’s still good to practice the following things to minimize the carbon build up in high mileage cars: use only high quality premium fuel, use the car on long distances too, change the engine oil after max. 8 000 km, and don’t be afraid to occasionally rev the engine properly-after warming it up of course.

To minimize issues with the turbochargers don’t use the start-stop system, don’t use this engine only for short city driving, and after a more dynamic driving keep the engine running at idle for at least 30 seconds before shutting it off.

All in all, with the proper care and mainly if you change that damn oil after 8 000 km, these engines can without bigger issues last up to approx. 200 000 km. After this mileage point, or on lower mileage abused cars with performance upgrades there is a high chance that the engine will have increased oil consumption:

V8 from 2011 ( M278) Bonus Issue

There can be an interesting issue with increased oil consumption because of worn cylinder walls and faulty pistons in this newer V8 engine. In this case the engine can develop a funny rattling/knocking noise as well which in other words means: EXPENSIVE REPAIR.

broken M278 idle knocking noise video

So if you hear the above noise from the engine then be ready to have it completely repaired – the price for this engine repair is somewhere around 5 000 € – 10 000 €.

But all of this stuff is not like extremely common YET. Nevertheless, it’s really important to avoid a car with this engine which has a performance upgrade-because this is the main reason for the worn cylinder walls and faulty pistons issue, and change that damn engine oil after MAX. 8 000 KM / 5 000 mi !!

The same goes for the S63 AMG with the M157!

S 600 V12

-The next on the list is the massive V12 with two turbochargers. It is awesome, it’s powerful, it’s not equipped with direct injection which is good, and there are also no major mechanical problems with it. However life is not a fairy tale so the maintenance of this engine is obviously more expensive. Or in other words, there is a high chance that sooner or later it will cost you bigger amount of that currency.

For example, this engine has 2 spark plugs/cylinder so there are 24 of them in total. This means that replacing them is obviously a bit more expensive and time consuming than on a regular V8. This would not be that big of a deal if the ignition coils would not be special and fucking expensive. The ignition coils are built into a rail which means that if one coil fails then you will have to replace the whole assembly. The new rail is expensive, but you can have it refurbished for a lower price and actually, the failure rate of this coil pack assembly is much lower than in the predecessor. But still, you have to be prepared that it can break, on the other side if you change those damn spark plugs after 60 000 km then you will minimize the failure of that damn ignition coil assembly.

how to remove the ignition coil assembly/replace the spark plugs S600 V12 video

info about refurbishing the ignition coil assembly

Then, if you buy mainly an older before facelift S600 then you have to be ready for various leaks. Some random oil pipe can leak here and there because of the age or corrosion, but that’s not even worth mentioning. On the other hand what is worth mentioning is a common possible leak related to the turbochargers on each side of the engine of course. There are 2 lines on the top of the turbocharger – an oil pipe and a coolant pipe. And the coolant pipe ending can leak. In this case you have to replace only a cheap o ring on the end of the coolant pipe, however you have to remove a bunch of stuff to access it which is time consuming. The only good thing is that there is no need to remove the engine, although the dealer will most probably remove the whole engine to fix this – which will in this case cost you 6,7 or 8 thousand of that currency. By the way in this case you should replace also the seal on the oil pipe, obviously.

Fixing this leak costs approx. $4 500 at an independent mechanic with removing the engine, without removing it should be up to $1 000

However if you are like really unlucky then not the o-rings, but the turbocharger itself can leak coolant from the core/freeze plug. In this case you have remove the engine and replace the whole turbocharger since these plugs are not available separately, but don’t panic since this is not like extremely common. (If you know a cheaper solution to repair this then write it into comments!)

just a funny video what it takes to remove and replace a turbo on this V12

And the next issue? Well there is nothing else really. I mean nothing else which would be special for this particular engine. But definitely check carefully for leaks which can be more expensive to fix, mainly if you are not familiar with this engine.

“Just remember: this engine is complicated, it generates a lot of heat, so some of the other rubber o-rings, gaskets, rubber hoses, pipes, valve cover gaskets can occasionally leak. Fixing these leaks is usually expensive since you have to remove a lot of things and sometimes the whole engine to fix them.”

S 400 Hybrid

The last from the non AMG versions is the S400 hybrid model which has the M272 V6 engine + an additional small hybrid system. This version was made from 2009 so the engine itself is not affected with the balance shaft sprocket failure, but it can have the other already mentioned M272 engine related issues.

And what about the hybrid system components? Well, they are definitely not that reliable as in a Toyota Prius. To top of that, some say that this hybrid version was built just to make the brand look greener/to improve the image of Mercedes, or in other words just to statistically lower the CO2 numbers of the whole S class model range. + just a handful of independent mechanics do actually have a clue what it is, how it works and what are the potential issues of this system

So, some of that weird expensive hybrid stuff can break. And especially the inverter failures are pretty common. The early symptoms of this inevitable failure are: not working start-stop system, long engine crank, occasionally not working AC, fault codes related to the hybrid system and later when the inverter completely breaks – the engine will shut off in the middle of the road and you won’t be able to start it. The new inverter costs around 4 000€, but there are remanufactured inverters from China for half of the price.

Then there is the hybrid battery which is located under the hood, it costs around 8 000 €, and it won’t last forever either. So all in all: if you don’t know somebody who is familiar with this hybrid system and you don’t want to spend thousands to fix it, then just avoid this hybrid version completely.

hybrid – remanufactured inverter from china

hybrid – how to remove the inverter video


Lastly, let’s briefly check out the AMG versions.

The before facelift S63 AMG made to 2010 has a naturally aspirated 6.2 l V8. This same engines was used in the CLK 63 AMG and in the E63 AMG as well, which means that it can have the well-known issue with the stretched or completely broken cylinder head bolts.

In these engines Mercedes used not the strongest cylinder head bolts which means that they can slightly stretch or break completely-causing leaking head gasket. In this case you will experience coolant loss due to coolant entering the combustion chamber via the blown head gasket and it will mix with oil. If you don’t fix this then you will end up with a destroyed engine, but Mercedes updated these head bolts so you can obviously replace them preventively. You either replace them one by one, without removing the heads and replacing the head gaskets – this is I would say the cheaper preventative solution. Or if you already experienced bigger coolant loss and coolant mixing with oil, then it’s better to remove the heads and replace the head gaskets too-this is obviously much more expensive.

This problem with the bolts is not like extremely common, so there are still even high mileage cars with the factory head bolts. On the other side there are already numerous cases of failed head bolts and some owners just replaced them preventively. At the end it’s up to you. But if the car still has the factory head bolts then you should at least check the coolant level regularly, and if you experience even the slightest coolant loss then first check for leaks, and if it’s not leaking anywhere then you should consider replacing the bolts ASAP.

“By the way, if you have this engine then it’s really REALLY important to have clean engine oil, so change it after maximum 8 000 km / 5 000 mi, and keep the oil topped up to the correct level, because if not – then you are increasing the risk of problems with the camshaft adjuster solenoids or prematurely worn camshafts! (symptoms of faulty camshaft adjusters: rattle at start up, misfires, check engine light)

The newer S63 AMG made from 2010 has a similar engine as the newer S500, so it has two turbochargers and direct injection and it has the same possible issues as the engine in the S500. The most powerful version of this S class is the S65 AMG which has a modified V12 from the S600 model, and it can have the exact same issues as the engine in the S600.

To end this, keep in mind that there is a bigger chance that all these AMG versions were abused, so the risk of unexpected wear and repairs is increased mainly when you buy one which is not from the first owner.

Diesel engines

320 CDI, 350 CDI

From the diesel engines the most reasonable choice is the 3.0 l V6. The reliability of this unit is not bad – it can withstand 300 000 or 400 000 kms, and I have seen numerous examples with more than 500 000 km as well, so except the usual diesel engine problems it doesn’t have many specific issues. But this doesn’t mean that it’s bulletproof, so there are 2 issues which are more common and which are worth mentioning:

inlet port shut off motor

-The first is related to the inlet port shut off motor or the swirl flap motor in other words. This motor can fail causing limp mode/reduced performance and an illuminated check engine light. This failure is caused by the seal on the turbocharger which will let the oil to slowly drip into this motor. how to fix the motor for free

oil cooler leak

-The next issue is the famous oil cooler leak caused by the seals attached to this oil cooler. You will definitely notice this leak since there will be traces of oil under the car and on the lower engine plastic panel + if you look at the bottom of the engine then you will see the black oil appearing at the rear of the block. Because of the heat the old seals can fail prematurely, and that’s why Mercedes updates these seals. The new updated seals are cheap, but that damn oil cooler is buried deep down in the middle of the engine(-between the heads) so you will have to remove a shit ton of parts to access the cooler(you have to remove various hoses, pipes, random boxes, the turbocharger + the intake manifolds). how to replace the oil cooler seals quick video

250 CDI

The 4 cylinder diesel engine is generally speaking not the best choice mainly because it can have more often issues with faulty injectors and with the prematurely worn timing chain. But long story short, the injectors were most of the time fixed under the warranty or under the recall, although the timing chain was not. However if both of these possible issues were fixed by the previous owner then this engine is definitely not the worst choice either.

420 CDI

The last engine is the big V8 with two turbochargers. Listen, this engine can serve you well unless you buy a car which had travelled to the moon and back or which was not treated properly. But either way, you have to be prepared that because of the bigger complexity and lack of space around the engine, the potential repairs are not going to be the cheapest + except the usual diesel engine problems it can have the exact same oil cooler leak as in the smaller V6, and there are occasionally cases of head gasket failures.

the advantage of this V8 compared to the smaller V6 is the additional power obviously, and also the fact that to replace the oil cooler you are removing less stuff, since the V8 doesn’t have the turbocharger on the top of the engine + there are no issues with the swirl flap motor either

All the diesel engines are equipped with DPF filters and from 2010 the V6 is equipped with the additional fantastic damn Adblue emission system as well. As usual the DPF can clog(this is nothing new), some pressure sensor on it can fail(this is nothing new either), however the additional Adblue system has more additional sensors and issues(and this can be something new even if it’s not).

On the picture below: AdBlue, NO START IN 731 km.

Adblue – this fantastic system can cause some additional issues, you can get various fault codes with the check engine light, the adblue level sensor can show low level even if the tank is topped up(-in this case it’s sometimes enough to recalibrate the sensor), then the adblue NOX sensor can be faulty. So be prepared to deal with this horrible system which is not going to let you start the engine if the adblue tank will be empty, or if the tank will be full but the sensor is going to read empty! Why? Cause the sensor is fuckin broken!

Check the diesel engines properly before buying, warm up the engine and try to accelerate with full throttle – the engine has to accelerate smoothly with enough power, without shuddering or jerking and without smoke from the exhaust!

Timing chain

All the engines are equipped with timing chain which can be usually worn just after 250 000 or 300 000 km, except the already mentioned petrol engines affected with the balance shaft horror story, the 4 cylinder diesel engine and the newer generation of V6 and V8 petrol engines which don’t have the check valves and new tensioners fitted. In all these cases the chain can be easily worn even at 150 000 km.


-Most of the engines are equipped with the infamous 7 speed automatic gearbox. All you have to know about it is, that in cars made to 2008 it can have more often issues with the conductor plate-specifically a speed sensor on it fails more often, but sometimes also some of the solenoids can fail.

Next the torque converter failures are also not uncommon and some mechanical parts inside the gearbox can be more worn too. So definitely check for: harsh downshifts in lower gears, shuddering, or harsh shifting in general which are the symptoms of the gearbox issues.

On the other side from 2009 they improved this gearbox which means that with regular oil changes it will work for a long time.

-The older 5 speed automatic transmission is not that fast or up to date as the newer 7 speed but it’s more reliable. Although if the previous owner never changed the gearbox fluid then it can have also issues with more worn torque converter /sometimes even after 100 000 – 120 000 km/ But if the oil in it was changed regularly then it can withstand more than 200 000 km without issues.

As the last things I would add that the car has to ride smoothly at all speeds /even highway speeds!!/ without vibrations or strange whining eventually growling sounds.

To summarize things up:

  • the best is to buy a car made from 2009
  • I would avoid the hybrid models completely
  • avoid cars with performance upgrades

+ it’s good to keep 5 000€ for the additional repairs, but if you are buying a V12 or one of the AMG versions then it’s good to keep twice that much money.

And as usual, if you have personal experience with this car or more information about it, then you can write it into comments!


  1. Great review

    I own this car myself. 2012 model with the 4.7 engine and 4matic lwb. Greatest car i have ever owned.

    Unfortunately owning this car has not been cheap. I was unfortunate enough to get the dreaded “M278 bonus issue” mentioned here(worn cylinder walls). and thus had to get a new engine. Mercedes does not sell only the block. This was extremely expensive i was fortunate to know ppl and get a good used engine only 20000km on it. But if i was to do this at the Dealership they would have charged around 75000euro just for the engine alone. This being a brand new engine. The nice thing is at least the car will last even longer now.

    Before the engine problem the control unit for the radio broke. This not only runs the radio but also the car “modes” and pretty much all other functions of the car, you can drive the car but not use any of it’s functions. Mercedes will not repair the radio unit and will only sell you a new one at the price of 10000euro. And since this is a very special unit and coded to the car you can not just buy a used one. And not many will repair this unit since it is quite advanced and unusual in the way it runs fiber optic cables in the car. Luckily Braybrooks in England will repair this unit for a fraction of the price. I could only find one other company that would repair this radio unit, that was in USA and that is to far for me. The unit might never brake, still something to keep in mind.

    Aside from those two problems i have had no other issues with the car. Service is surprisingly cheap even at the dealership.

    Tough if you only want this car for the ride and equipment i would definitely go for a diesel. As far as i know these tend to have less problems and when they do, less expenses. But with that being said it will never be the same as a V8 🙂

    Still with all the problems i faced with the engine and radio unit i will never regret owning this car and will continue to own it for a long time.

  2. love your reviews. love the random swearing. as i read this i hear your voice bitching about the issues lol. keep at it. great place for NO BS info. though i cannot figure out why my car jerks or chugs on reverse and forward on cold start.


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