There are 1 owner-reported powertrain & transmission complaints for the 2021 BMW 4 Seriesin NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
The contact owns a 2021 BMW 430I. The contact stated while stopped at a traffic light, the light turned green; however, when the accelerator pedal was depressed, the vehicle failed to respond as intended. The contact stated that the power train warning light was illuminated. The contact turned off and restarted the vehicle, shifted to drive(D); however, the vehicle failed to respond. The contact had the vehicle towed to a dealer to be diagnosed. The dealer determined that the rear differential oil had leaked out causing the differential to seize. The contact was informed that the rear differential needed to be replaced. The vehicle was not repaired. The manufacturer was informed of the failure. The failure mileage was approximately 33,000.
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 26, 2026