Audi A6 (C6/4F) 2004-2011

On one side there is this spacious, safe, affordable and still not bad looking car with a well-built interior, which can be equipped with a great 4WD system.

But on the other side this exact same car:

• can leave you stranded far away from home
• has some weak points which can lead to a significant engine or electronics damage
• can be equipped with a couple of extremely overpriced spare parts-while the high price is not justified at all

This can sound a bit scary, but with preventative maintenance and with a little bit of luck it’s absolutely not hard to reach 400 000 km / 248 000 mi and more + even avoid most of the issues. And actually, currently there are 52 of these vehicles for sale in Germany which have more than 400 000 km (and 52 is actually not a low number for a German used luxury car with this kind of a mileage).

The Audi A6 C6 was available as a:

Saloon/sedan

Avant/estate

A6 Allroad

Long version – extended wheelbase saloon models with bigger rear seat legroom made exclusively for China

Of course there is also the S6 (S6 review here) and the RS6, but let’s just focus on the regular models.

There is nothing special about the saloon or the Avant models and actually there is nothing really special about the A6 Allroad either (unlike the previous generation Allroad which was a highly modified A6). Since this is just an Avant version which is standardly equipped with a plastic body kit, with the Quattro 4WD system and with the adaptive Air suspension, nothing more nothing less (low range gearbox or stronger body? forget about that). The plastic body kit usually has a default grey look, however it can be also painted in the color of the body – this was a factory option back then.

Interior

The interior of this A6 is spacious, well built and user friendly even at this day and age.

The dashboard is ergonomically inclined to the driver and all the switches are where they should be. However you have to get used to all the buttons on the AC panel and on the MMI system panel. But after getting used to these buttons you can with no problem choose the right category or change the temperature easily even while driving which is something you can’t really do on a touchscreen. + The MMI multimedia system is faster and it has also nicer graphics than the early iDrive in the BMW 5 series E60. It’s also worth mentioning that the facelifted A6 made after 2008 got an updated MMI system which has even better graphics and faster navigation system.

Moving on to the materials quality, everything in the interior is most of the time in a great condition without noticeable wear. However there are some parts which can be worn out more often specifically:

• the windows control switch
• the MMI center button surface
• the keyless start stop buttons
• the side part of the driver’s side door panel can be often cracked
• in the oldest cars the top layer of the decorative wood trim can delaminate/disintegrate
• the back plastic covers of the front seats can get loose – the glue gets weak over time
• sagging headliner starts to be a problem too

When it comes to build quality, yes, it really is on a very high level and it’s definitely better than in the BMW 5 series E60. Almost everything feels really solid starting with the seat side plastic covers thru the dashboard and to the door panels-which are like literally rock solid unless someone disassembled and badly assembled these parts of course. But nothing is perfect, so cars equipped with the stiff factory sport suspension can make rattles from the dashboard on bad quality roads, and the front center armrest can make creaking noises in hot weather.

The standard equipment (in Europe at least) contains basically nothing spiced with a standard monochromatic multimedia system display from the previous century. The optional equipment on the other hand contains almost everything including:

• soft-close doors
• double glazed windows
• solar sunroof (powers only the blower motor in summer when the ignition is off)
• leather seats with leather dash
• ambient lightning package
• electrically adjustable and heated steering wheel
• parking camera
• and all that other stuff

But surprisingly there are also things you can’t get in this car, like: ventilated front seats, head up display, night vision, massage seats or heated windscreen. This is interesting, since all these things were available in the BMW 5 series E60 – except the heated windscreen. On the other side most of the people won’t necessary need these things, although the ventilated front seats are definitely a great feature in the summer…

Fun fact: this is the first A6 which can be equipped with a leather covered dashboard, since this feature was not available in the older A6 C5 and it’s also not available in the successor of this car – the newer C7 model. But the newest C8 models can be again equipped with this feature.

When it comes to music interface, or connectivity, or music user friendliness, whatever you call it, this car is not that hopeless! There is of course the usual CD changer which nobody really uses nowadays, but you can also find cars which are equipped with a “magic box in the glove box” – called the AMI (Audi Music Interface). With this interface you can connect your phone thru the usual AUX cable, or you can connect an USB flash drive and play the music thru these sources. Cars after the facelift got an update in this field – so they can be equipped with the updated version of this AMI in which you can put SD cards (on the picture below).

Lastly, there are 3 types of front seats you could have in these cars:

Possible problems

1. Some electronics

-The usual stuff like the door locks, the window regulators or the keyless entry door handles can of course break, so first thing first check these basic features. (how to remove the front door panel video)

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2. Front door speakers

-Then it’s good to check the main front door speakers which can rattle, so turn up the volume and listen for a speaker rattle. If you hear it then you should know that it’s caused by a plastic speaker dust cap which is glued on the speaker. The glue gets weak over time→the dust cap gets a little loose→and you get a rattle. In this case you can remove the dust cap and re-glue it back, or you can buy a new speaker, whatever you want.

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3. Steering lock

-After this there is the electronic steering lock which can fail and which can leave you stranded since you won’t be able to start the car. The faulty steering lock can be replaced by the dealer, it can be repaired or it can be even deactivated if you find the right person. I did a separate video about this issue so you can find out more here.

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4. Seatbelt buckle

-Then there is the seatbelt buckle which can be faulty. This will cause the annoying seatbelt warning noise to not go off even if your seatbelt is fastened. Surprisingly the new buckle is not that expensive, but you can also find someone with a diagnostic computer to deactivate this warning completely.

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5. AC system

-It’s also good to check the AC properly, because if one side is cooler than the other while the temperature is set to the same value on both sides, then this issue is usually caused by the heater valve which can clog and get stuck. In some cases it’s enough to disassemble and clean it but if this won’t help then you will need to replace it. To minimize the chance of this issue happening it’s good to occasionally turn the temperature on both sides all the way down, wait a little and then turn it all the way up to make the valves move. Since if you won’t change the temperature a lot then the valves won’t move that much + if you won’t change the coolant regularly then the debris in the coolant will clog the valve. So of course you should also keep the coolant clean, which means that you should change it completely at least every 4 years. Also make sure you do have clean cabin air filters → How to replace the cabin air filters video.

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6. Electronic parking brake

–Check the electronic parking brake which can occasionally seize up mainly if the owner not used it regularly, so at least engage and disengage it a couple of times

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7. Tail light condensation/water leak

-Mainly on the saloon models there can be an issue with the tail light condensation/water leak. This can be fixed by either replacing the black seal which is on the plastic cover → which is attached to the back of the light (on the picture below). Or if this wont help, then you can put silicone around the edges of the light-where the outer-red cover meets the plastic housing.

Avant / estate additional issues

Overall there are not that many issues as you can see, but if something seems like it’s too good to be true then it’s most probably not true, or something like that, so the Avant versions can have more additional issues as a bonus:

tailgate, wiper motor, leak

• The rear windscreen wiper motor can fail because of the washer fluid which will leak right into the motor-which will break completely. But this washer fluid wont leak only into the motor but also into the tailgate, so if nobody is going to fix this then the tailgate slowly starts to rust because of the accumulated washer fluid, beautiful. But even more beautiful scenario is, when you get water leak into the tailgate from the inner tail light seals since as they age they can let the water in too.

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washer fluid leaks

1. Interestingly the washer fluid can leak not only from the rear washer motor but also from the hose which is right next to the trunk lid hinge. This is more serious since the fluid will leak right into the amplifier, into the radio module and into the navigation system DVD module. All these modules are connected which means that even if one fails completely then your whole MMI system won’t work at all. However the only good thing is, that there was a recall specifically for this issue so most of these cars do have already fixed this hose – if the car has a dealer maintenance history of course.
2. And the last washer fluid leak can occur right under the driver’s seat. Right under the carpet is a plastic washer fluid hose which can leak. This leak is also not the best since you won’t even know about it until the carpet and the area under it will be soaked with the fluid, or until your bluethoot handsfree won’t work properly since the bluetooth module and also a wiring loom are next to his hose. The bluetooth module can be easily completely or partly ruined because of this leak. On the other side this leak can be easily fixed using a little bit of imagination and improvisation. All you need to do is cut out the plastic hose and find a smaller short random hose which you can connect to the plastic hose. And by the way, you need to remove the seat and some plastic surrounding trim to access this area.

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As a bonus the Avant version has another 2 age related cosmetical features which are related to fading.

-First of all, the inner rear lights on the avant version are made from a cheaper plastic, so in a lot of cases you can see that they are faded like on the picture below.

-But the rear inner lights are not the only thing which is fading in the rear of the avant version, since the rear glass edges are also fading, I mean what the fuck. I have seen this kind of glass fading in other cars as well, but not in a big scale like this. I have seen a huge amount of these A6 avants with this “feature”, and it looks like shit, what can I say?

Suspension

Let’s continue with the suspension which can be good but it can also ruin your day. There are 3 types of suspension in these cars:

• standard suspension

• s-line sport suspension

• adaptive air suspension

As in most of the other cars there are no extraordinary issues with the shock absorbers of the standard or the sport suspension, just check them for leaks of course. Also keep in mind that plenty of the owners complain that the sport suspension is very stiff so if you have bad quality roads around you then it’s better to choose a car without this suspension type.

The self levelling adaptive air suspension is on the other side a different story. You can adjust not only the ride height but also the stiffness of the shocks, so in comfort mode it is comfortable but in dynamic mode it gets noticeably stiffer. +In the Allroad models you can adjust the ride height a little higher than in the regular versions equipped with this suspension, but this of course doesn’t mean that it will magically become an off road vehicle…

The lifetime of the front air struts is approximately 10 years which means that after this point you are on borrowed time since they can fail at any time. Of course they can withstand even more than 10 years but mainly if the car was not used on winter salty roads, since not only the age but also the road salt reduces the lifetime of the air struts. All in all, don’t be that guy who has a 10+ years old A6 with an air suspension and who doesn’t have a clue that the air struts can leak at any time, because surprise, surprise, they can! A low rider A6 with a leaking air strut is not something which would cheer you up, because in this case you can’t drive it anywhere. The brand new genuine air strut costs a bit more than 1 600 € which is a lot, but it is gonna withstand at least another 10 years. Of course you can also buy a well known aftermarket part which is still not the worst idea, but buying a no name aftermarket or a Chinese air strut is definitely a bad idea, unless you want to be a test dummy.

While the front air struts are a single unit – so the shock absorber and the air strut is combined, then in the rear they are separated – so the air strut is a single unit as well as the electronic shock absorber.

The rear air struts usually won’t last that long as the front, which means that they can start to leak earlier than 10 years, but luckily the rear air struts are not very expensive. On the other side the rear electronic shocks are really overpriced + after 200 000 km or even before this mileage point they will leak. So if you are buying an A6 which is equipped with the air suspension then check the rear shocks for leaks, because one new genuine electronic rear shock absorber costs more than 800 €, and that really is a lot. Unfortunately currently there is no well-known aftermarket company which would make these rear shocks. On the other side there are companies which are selling cheaper refurbished rear shocks and there are also those Chinese made shocks available of course.

Usually if you got an early leak in the system then the car will drop overnight in dynamic, automatic or comfort settings, but if you leave it in the higher modes like: allroad or lift then it won’t drop.

Also keep in mind that the suspension height sensors can seize up over time – causing various creaking noises (eventually they can also break), so after buying it’s good to clean and re-grease the ball joints on them.

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The other suspension components can easily withstand more than 200 000 km, only the front upper control arms and the front drop links can be worn earlier + the wheel bearings can fail too, but of course check all the suspension components visually and listen for weird sounds during driving.

“Because of the engine which is mounted after the front axle the handling of this car in corners is, well, not awesome, which means that the rival of this A6 – the BMW 5 series E60 has much better handling with much better weight distribution and with better steering response/feel as well. On the other side because of the Quattro 4wd system, because of the complex suspension design and because of the bigger weight, the stability of this A6 on the highway or on bad quality roads even at higher speeds is very impressive. And it doesn’t matter if it’s raining, snowing or if there is an apocalypse outside. So while in bad weather everybody will go in the right lane on the highway, you can go faster in the left lane without any worries (of course for this kind of an artistic performance it’s necessary to have good quality winter or summer tires, ok?).”