There are 4 owner-reported powertrain & transmission complaints for the 2018 Audi A4in NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
See attached document for complaint
While driving there was an internal failure of the front differential which caused debris to fly out and the debris then punctured the transmission according to the diagnosis on an Audi dealership. The car jerked to a stop and would not move. If this happens at high speed it represents a sever safety risk to the occupants. The vehicle has been inspected by the manufacturer and insurance representatives as well as by a dealer. There were no warning lamps, messages or other symptoms and this happened with no warning.
The all-wheel-drive clutch in the vehicle had to be replaced. The symptoms were heavy vibrations or thumping when starting to drive forward from a stop with the wheels turned in either direction. A dealership - New Country Audi of Greenwich - did the repair at a cost of $4,308.85 (including tax). This drivetrain failure occurred at less than 48,000 miles. The vehicle came with a 50,000 mile or 4 year warranty. Since it was in service for over 5 years, this defect was not covered under warranty. There is a Techical Service Bulletin on this issue, number 39 21 43 2059057/4 July 16, 2021. The dealer confirmed my issue was indeed the same as that addressed in the TSB. It seems to me that a major known issue occurring at less than 50,000 miles is a defect. I do not know if it is ultimately a safety hazard, but it seems it could become dangerous if not addressed. For reference, I am attaching the TSB and the repair invoice.
ENGINE MALFUNCTION PREVENTED THE VEHICLE TO ENGAGE AND A SIGNIFICANT LAG. CORRECTION OF THE FAILURE HAS BEEN ATTEMPTED TWICE AND A THIRD ATTEMPT TO CORRECT MALFUNCTION IS CURRENTLY IN PROGRESS WITH NO MOVEMENT AS OF YET. GAS TANK HAS BEEN DRAINED AND REFILLED AND DID NOT CORRECT ISSUE. DEFINITELY NOT A GASOLINE TYPE ISSUE.
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
Data synced from NHTSA on Apr 25, 2026