Audi A4: Common Problems, Fault Codes & Repairs Everything for the Audi A4 in one place — its common problems and reliability, the fault codes owners see most, and the tools to diagnose them. Audi A4 fault codes Audi A4 P0171 Audi A4 specs & capacities Audi A4 — Fuse box location & guideAudi A4 — Oil capacity & typeAudi A4 — Tire pressureAudi A4 — Bolt pattern & wheel sizes Recommended tools Automotive MultimeterCompression TesterBattery & Charging System Tester Read your code: OBD-II scanners →