Common Problems with the Audi A6
FixMyCar discusses common problems with the Audi A6 and average repair costs.
Compare Audi A6 repair quotesEllie Dyer-Brown
Tuesday February 24 2026
9 min read
The Audi A6 is a stylish executive car launched in 1994 and now in its fifth generation.
This guide examines known issues with the A6, providing owners and potential buyers with insights into specific faults and their average repair costs.
In a nutshell: Common problems with the A6 include gearbox issues, electrical and infotainment glitches, sensor problems, rear light water ingress and AdBlue faults, with some repairs becoming expensive quickly. Overall reliability is mixed to below average in recent surveys, so buying a well-maintained example with a strong service history is especially important.
What's wrong with the Audi A6?
Drivers are searching online for information about the following problems.
Audi A6 AdBlue system fault
An AdBlue fault message or dashboard warning light could be caused by a faulty pump or injectors, sensor issues or contaminated fluid. Symptoms typically include reduced performance and increased emissions. Some cars may enter limp mode, which limits power until the problem is fixed.
Learn more about AdBlue and how it works.
Audi A6 central locking fault
Problems can sometimes arise with the central locking system, including doors not locking or unlocking and the key fob not functioning properly. There are several possible causes, ranging from a faulty actuator to corroded wiring.
Audi A6 saloon common problems
There aren’t many faults that are exclusive to the saloon version, because the A6 saloon and Avant share most of the same engines, gearboxes and electronics. The main body-style issue worth checking is rear light water ingress (particularly on some 2011-2018 cars), as replacement light units can be expensive.
Audi A6 Avant common problems
It's the same story with the Avant - it shares the same problems as the saloon version because it has the same mechanical underpinnings.
Recent recalls
| Recall number | Date | Reason |
|---|---|---|
| R/2025/508 | 14.11.25 | On affected vehicles an important connection in the seat belt buckle may not have been produced correctly during the assembly process. |
| R/2025/463 | 24.10.25 | On affected vehicles there may be defective battery modules which may result in a fire hazard when charging the high-voltage battery. |
| R/2024/495 | 19.12.24 | On affected vehicles battery modules may become defective over the course of the vehicle's service life, which can create a fire hazard. |
| R/2023/317 | 27.10.23 | On certain vehicles an incorrect bracket for the side airbag was fitted in the left front seat. |
| R/2023/027 | 20.01.23 | The fuel gauge may not show the drop in fuel level correctly during vehicle operation. |
| R/2022/169 | 10.06.22 | It is possible that the engine control units were fitted with semiconductor components which do not meet the specifications. |
| R/2022/132 | 04.05.22 | The mesh size of the oil strainer in the oil supply for both turbochargers is too small. |
| R/2022/036 | 14.02.22 | Following a previous campaign the toe and/or camber values on the rear axle may in certain circumstances incorrectly be changed without this being noticed. |
| R/2021/236 | 25.06.21 | One or more nuts which do not meet the specifications may have been fitted on the rear axle suspension links. |
| R/2021/117 | 26.03.21 | In the event of an accident requiring the vehicle’s front passenger airbag to be activated the airbag might not inflate fully. |
| R/2020/372 | 08.12.20 | Faulty crash sensors for airbag/restraint systems may have been fitted in both of the front doors. |
| R/2020/265 | 02.10.20 | It is possible that moisture may enter the belt-driven starter-alternator. |
| R/2020/138 | 30.06.20 | It is possible that moisture may enter the belt-driven starter-alternator. |
| R/2019/175 | 03.06.19 | Hinged towing bracket on which the locking mechanism in the hinge module could be faulty. |
| R/2019/099 | 18.03.19 | It is possible that fuel may escape from one or both fuel rails (low-pressure side). |
| R/2018/363 | 17.12.18 | There is a possibility that the glass bonding on the panoramic sunroof is not bonded correctly. |
| R/2017/115 | 01.05.17 | Foreign particles in the engine coolant can lead to a blockage in the additional coolant pump and cause the pump to overheat. |
Audi A6 2004-2011 problems
1. Contaminated transmission fluid
Cars of this generation can judder when pulling away if the transmission fluid has been contaminated with coolant - a problem that usually happens in models with an ATF cooler integrated into the radiator.
What repair is needed for contaminated transmission fluid, and how much does it cost?
You'll need to replace the radiator (average price: £328.82) and the ATF filter. If that doesn't work, a full automatic transmission replacement may be required, which will likely cost thousands.
2. Worn propshaft bearing
A6 models with a quattro four-wheel drive system can suffer from a worn centre propshaft bearing. The most common symptom is a whining noise from beneath the vehicle when driving at around 30-40mph.
What repair is needed for a worn propshaft bearing, and how much does it cost?
The bearing needs to be replaced, which can cost between £150 and £500.
3. Oil leak
A drop in oil pressure is often linked to a problem with the oil filter cover and filter housing, which allows oil to leak out.
What repair is needed for an oil leak, and how much does it cost?
Replacing the filter cover and housing should do the trick. It's also worth doing an oil change at the same time. In total, you can expect to pay £350-£800.
4. Faulty starter motor relay
Some A6 owners experience trouble starting the engine due to a faulty starter motor relay.
What repair is needed for a faulty starter motor relay, and how much does it cost?
A mechanic will disconnect the battery and check the starter motor wiring. If it's damaged, they will repair it; if not, the starter motor may need to be replaced. The average starter motor replacement price on FixMyCar is £384.19.
Audi A6 2011-2018 problems
1. Oil consumption
Excessive oil consumption is a common complaint from A6 owners, who find themselves topping up the engine oil more often than they’d like. This is especially common in older models, which tend to use more oil as they age.
What repair is needed for excessive oil consumption, and how much does it cost?
Using a lot of oil isn’t necessarily a sign of a problem, but it’s worth checking whether your car has an oil leak, particularly if it’s one of the newer fourth-gen models.
2. Automatic gearbox issues
S Tronic and Multitronic automatic gearboxes must have their oil changed at or before the recommended interval of 38,000 miles; otherwise, they can develop serious problems caused by excessive friction and overheating.
What repair is needed for automatic gearbox issues, and how much does it cost?
A repair might be possible depending on the extent of the damage, but it will be expensive. The average price of an auto gearbox repair for an A6 on FixMyCar is £952.90; a replacement will likely cost several thousand pounds.
3. Electronic handbrake failure
The electronic handbrake can sometimes fail to release, which can leave the car stuck until the fault is cleared.
What repair is needed for electronic parking brake failure, and how much does it cost?
A garage will usually start with a scan and software update (if applicable), but if a motor/caliper/module has failed it may need to be replaced. Fixing an electronic parking brake typically costs between £300 and £900.
4. Rear light water ingress
Water can sometimes get into the rear light units, and replacing them can be pricey.
What repair is needed for rear light water ingress, and how much does it cost?
A mechanic will check seals, vents and wiring first, but the usual fix is resealing or replacing the affected rear light cluster. Replacing the unit can cost anywhere from £200 to over £400.
Audi A6 2018-present problems
Drivers have encountered the following problems with fifth-generation Audi A6.
1. Infotainment glitches
Owners report issues such as phones not connecting properly and screens that flicker or go blank, which can also take out other functions that run through the central display.
What repair is needed for infotainment glitches, and how much does it cost?
The first step is usually a software update or reset and a scan to see whether it’s a coding or module fault. If it’s hardware (screen/head unit/control module), the fix can escalate quickly. A standard diagnostic test averages £61.87.
2. Faulty sensors
A6 owners have reported issues with various sensors, including the mass air flow sensor (pictured above), turbo pressure sensor and parking sensors.
What repair is needed for faulty sensors, and how much does it cost?
A garage will normally diagnose the fault code(s), then replace the failed sensor and calibrate as needed. A diagnostic test averages £61.87 on FixMyCar
3. Mild-hybrid electrical system fault
On some A6s with the 48V mild-hybrid setup, moisture in the mild-hybrid system is a known issue.
What repair is needed for a mild-hybrid electrical system fault, and how much does it cost?
This typically involves an electrical diagnosis first, followed by repair or replacement of the affected wiring/connectors/modules (and sometimes a battery-related fix). An electrical fault diagnosis costs £73.58 on average.
4. Turbo failure
Turbocharger problems, often caused by oil contamination or starvation, can cause a range of symptoms, including loss of power, whistling noises, thick exhaust smoke, limp mode and the check engine light.
What repair is needed for turbo failure, and how much does it cost for an Audi A6?
Replacing a turbo can cost anywhere from £450 to several thousand pounds. The average price of a turbo replacement on FixMyCar is £774.79.
Years to avoid
There aren’t any universally agreed Audi A6 years to avoid, but reliability data and used-car guidance suggest being more selective with certain generations and early model years.
Early C7 models (2011-2014) - These are the riskiest years for expensive faults, with known issues including automatic gearbox problems, electronic parking brake faults and rear light water ingress. A full service history is especially important on these cars.
Early C8 models (2018-2020) - These years are more prone to electrical and infotainment glitches, so check for evidence of software updates, repairs and careful maintenance before buying.
Older C6 models (2004-2011) with patchy history - For this generation, condition matters more than the registration year. The main risk is buying a poorly maintained car with age-related faults rather than avoiding one specific model year.
Find out what to look for when buying a used car.
Is the Audi A6 reliable?
The 2025 What Car? Reliability Survey put the 2018-2025 A6 in 14th place out of 23 cars in the executive car class, with a score of 90.2%. Audi, as a brand, finished in 22nd place out of 30 manufacturers.
In the 2024 survey, the same A6 generation finished in 22nd place out of 24 vehicles in the executive and luxury car class, with a score of 82.5%. Its predecessor didn’t fare much better, coming in last place in a survey from a few years ago.
While the A6 has many positive attributes, reliability isn’t one of them.
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- Audi
- Common Problems
Ellie is FixMyCar's Content Manager. She has over three years of experience writing about cars and regularly collaborates with automotive experts to provide trustworthy advice for drivers that is easy understand. Her work has been featured in Yahoo! Finance, iNews, The Daily Express and The Sun. She has a BA in English literature and an MA in creative writing from Durham University. Outside of work, Ellie follows F1 and eagerly awaits Ferrari's next era of dominance in the sport. She drives a Suzuki Swift.