Models · Audi
Audi RS4 B9 buying guide
The B9 RS4 Avant went on sale in the UK in 2018 with a 2.9 litre twin-turbo V6 co-developed with Porsche, matching the old V8's power with far more torque, an 8-speed automatic and quattro. A 2020 model year facelift changed the styling and cabin, with the mechanicals unchanged.
The versions
- 2.9 TFSI twin-turbo V6 (EA839), 450PS and 600Nm
- 8-speed tiptronic torque converter automatic (ZF 8HP), replacing the previous S tronic
- quattro with a sport rear differential, standard on all UK cars
- Avant only
- Facelift for the 2020 model year: new front end and wider arches, a 10.1-inch touchscreen in place of the rotary controller
- Competition (2022, 75 UK cars) and 25 Years editions with coilovers and carbon-ceramic brakes
What to check on a B9 RS4
3 model-specific things to look at when you view one. They're a starting point, not the full inspection.
Cold start and warm-up
What to look for: Start the car from cold and watch the rev counter: the idle should settle rather than wander. Pull away gently while it's still cold and feel for stuttering or kangarooing. On the drive, check the temperature gauge reaches normal and stays there.
Why it matters: Owners report thermostats sticking open or shut, a random idle speed on start-up and stuttering when cold. They're known issues with known fixes, and a car that starts and warms up cleanly is a good sign.
The water pump
What to look for: With the bonnet open, look at the pulley on the front of the engine that drives the water pump and count its bolts: six means the revised pump, four the original. Check the coolant tank is between its marks and look for dried coolant residue on the front of the engine and the left-hand cylinder head.
Why it matters: The original pump on this engine family, listed for the RS5's identical 2.9 V6, can leak internally, drawing coolant into the vacuum system, where it can trigger a boost fault and in time cause damage. Audi released a revised pump with a six-bolt pulley, so a car with it fitted has had this dealt with.
Rocker arms on early cars
What to look for: Note the build date. On cars built before 2019, ask whether the rocker arms have been replaced with the upgraded parts, and look for the invoice.
Why it matters: On the RS5, which uses the same 2.9 V6, a rocker arm problem affects some cars built before 2019. It isn't especially common, and the fix is upgraded rocker arms, often done alongside a service and a new water pump. Paperwork for the work settles the question.
Also in the full guide
- Engine warning light and sensors
- Suspension knocking
- Gearbox changes and leaks
- The cold start, test drive and paperwork checks for the exact version you're viewing
The full guide to the B9 RS4
The CrankSight guide walks you round the car on your phone at the viewing, with every check for the exact version you're looking at: what to look for, where to find it, and what anything you find is likely to cost. As you go it builds an assessment of that car, and if you view more than one, it lines them up side by side.
£29 for the model, used on as many cars as you like, delivered within 72 hours or your money back.
Other generations
General points for the model, last checked October 2026. Every car is different, so treat this as a guide to what to look at, not a verdict on any car. CrankSight is independent and has no connection with Audi.