Part of the Audi A4 B9 (2015–2024) guide: best and worst years compared.
2021 Audi A4 petrol: common problems and MOT failures
What MOT testers find on the petrol Audi A4 first registered in 2021 (petrol cars only): we looked at the 7,983 MOTs these cars had during 2023–2025. Plus known faults and what to look at before you buy one.
What goes wrong more than usual on a 2021 Audi A4 petrol?
Parts flagged at MOT more often on the 2021 Audi A4 petrol than on all cars registered in 2021.
- Coil springsnull× usualAudi A43% All 2021 cars0%
Failed outright at MOT: 0.2%, against 0% of all 2021 cars. The rest were advisories or minor defects.
Rough price £175–£400 (pair, one axle) ClickMechanicAt the viewing: Look behind each wheel for a snapped spring coil, and listen for a clunk or twang when turning the wheel lock to lock with the car stopped.
Brake discs: 2.6% here, against 6.1% of all 2021 cars.
Common 2021 Audi A4 petrol MOT failures and advisories
The share of 2021 Audi A4 petrol MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.
- Tyres29% of testsRough price £70–£150
At the viewing: Check the tread on all four tyres, including the inside edges, and look for cracks or bulges.
- Brakes7% of testsRough price £150–£350
At the viewing: Look for a lip on the disc edges and feel for judder or pulling when braking firmly from about 40mph.
- Suspension5% of testsRough price £120–£400
At the viewing: Listen for knocks over speed bumps, and look behind each front wheel for a snapped coil spring.
- Wipers, windscreen and mirrors3% of testsRough price £15–£250
At the viewing: Check for chips in the driver's view, and test the wipers and washers.
- Seats and seatbelts3% of testsRough price £80–£250
At the viewing: Pull each seatbelt sharply. It should lock, and retract cleanly.
- Lights and electrics2% of testsRough price £10–£80
At the viewing: Ask a friend to check every light, including brake lights and indicators, while you operate them.
Known faults on the 2021 Audi A4 petrol
Reported by owners, mechanics and buying guides for this model and age. Check which engine the car has, as some apply to one engine only.
- Mild-hybrid models
Starter-alternator recall (mild hybrids)
Moisture could get into the starter-alternator on mild-hybrid cars, which led to two recalls in 2020.
At the viewing: Ask an Audi dealer or the seller to confirm the recall work was done.
- All engines
Seat and airbag recalls
There were recalls for front seats and seat frames, and for airbags and seatbelt pre-tensioners that might not work.
At the viewing: Make sure the airbag light goes out, and ask for proof of recall work.
- All engines
Stop-start problems
Some owners report problems with the stop-start system.
At the viewing: Watch the engine stop and restart smoothly at junctions, with no warning lights.
- All engines
Trim rattles
Rattles from the cabin trim are a common complaint.
At the viewing: Drive on a rough road and listen around the dashboard and doors.
- Avant estate
Powered tailgate faults (Avant)
The powered tailgate on Avant estates can play up.
At the viewing: Open and close it several times with the button and the key.
Questions to ask the seller before buying a 2021 Audi A4 petrol
Ask before you travel to see it. A seller who knows the car will have answers, and receipts.
- Any recent work on the coil springs? (Flagged at MOT null× as often on the 2021 Audi A4 petrol as on other cars the same age.)
- Can I see the service history and receipts for any big jobs?
Looking at an Audi A4?
Check the actual car: its own MOT history, mileage and what to ask the seller. Free, no sign-up.
Other years
Every year of the Audi A4 compared
| Year | MOT tests | Most flagged |
|---|---|---|
| 2026 | – | Too new for MOT data |
| 2025 | – | Too new for MOT data |
| 2024 | – | Too new for MOT data |
| 2023 | 362 | Tyres 19% |
| 2022 | 7,043 | Tyres 28% |
| 2020 | 25,381 | Tyres 28% |
| 2019 | 39,575 | Tyres 30% |
| 2018 | 40,399 | Tyres 28% |
| 2017 | 63,211 | Tyres 28% |
| 2016 | 65,764 | Tyres 29% |
| 2015 | 48,854 | Tyres 31% |
| 2014 | 50,261 | Tyres 31% |
| 2013 | 47,748 | Tyres 32% |
| 2012 | 40,105 | Tyres 33% |
| 2011 | 41,085 | Suspension 39% |
| 2010 | 38,856 | Suspension 40% |
| 2009 | 38,253 | Suspension 41% |
| 2008 | 45,736 | Suspension 47% |
| 2007 | 45,101 | Suspension 48% |
| 2006 | 38,799 | Suspension 50% |
| 2005 | 22,925 | Suspension 49% |
| 2004 | 19,785 | Suspension 50% |
| 2003 | 11,574 | Suspension 52% |
| 2002 | 6,124 | Suspension 54% |
| 2001 | 2,778 | Suspension 48% |
| 2000 | 2,815 | Suspension 45% |
| 1999 | 2,189 | Suspension 46% |
| 1998 | 1,448 | Suspension 45% |
| 1997 | 812 | Suspension 49% |
| 1996 | 551 | Suspension 46% |
| 1995 | 174 | Brakes 40% |
Where this comes from: the DVSA's anonymised results for every MOT test done in Great Britain during 2023–2025, counting the MOTs of Audi A4 cars first registered in 2021. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score