NHTSA Complaint #11685069 — 2015 BMW 435I

I am submitting this complaint regarding a 2015 BMW 435xi (N55 engine, ~79,000 miles) that suffered a sudden and complete engine failure due to the oil pump drive chain. While driving at highway speed, the vehicle experienced an instant loss of oil pressure and engine seizure without any warning lights or prior symptoms. I barely managed to steer the car to the shoulder and avoid being struck by surrounding traffic. This was a serious safety hazard, as the loss of power and steering control occurred in active highway conditions. Inspection revealed a catastrophic internal failure of the oil pump drive chain. This is not related to neglect, lack of maintenance, or external damage—the vehicle had received an oil service at a BMW dealership only two months prior. Importantly, the N55 engine uses the same oil pump chain and guide architecture as BMW’s N20/N26 4-cylinder engines. BMW has already acknowledged premature failures of this system in those engines and provided extended warranty coverage. The fact that this defect is now occurring in the N55 platform demonstrates a broader systemic issue. This failure at relatively low mileage creates a significant safety risk to drivers and passengers, as well as other vehicles on the road. A sudden seizure of the engine at highway speed leaves little to no opportunity to maneuver safely and avoid collisions. I urge the agency to investigate this issue as a potential design defect affecting the N55 engine family. BMW should be required to provide recall or warranty remedies similar to those extended for the N20/N26 engines. Thank you for your attention to this serious safety matter.