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What 38 owners told NHTSA about the 2014 Mercedes-benz Gl-class

These are the actual owner complaints behind this car’s reliability verdict, filed with the federal government, unedited. They’re unverified reports, not confirmed defects: read them as leads for your pre-purchase inspection, not a diagnosis.

All (38)Crash / fire / injury (1)Engine (11)Electrical system (4)Steering (4)Brakes (3)Transmission & drivetrain (3)Visibility & wipers (3)Body & structure (2)Engine & cooling (2)Seats (2)Suspension (2)

3 of 38 complaints match · Transmission & drivetrain · clear filters

Jul 5, 2023Engine & coolingTransmission & drivetrain

The contact owns a 2014 Mercedes-Benz GL350. The contact stated that while inspecting the vehicle, there was oil leaking underneath the vehicle. Additionally, the check engine warning light was illuminated while operating the vehicle. The vehicle was taken to the local mechanic who diagnosed the vehicle and determined that the oil cooler seals were faulty and needed to be replaced. The seals were replaced, and the vehicle was repaired. The vehicle was later taken to the local dealer for transmission failure. The manufacturer was notified of the failure. The failure mileage was 140,000.

NHTSA ODI 11530486

May 23, 2021Transmission & drivetrain

Oil leaking and wicking into camshaft position sensors, camshaft magnets, O2 sensors, engine wiring harness and ultimately, the ECU is destroying all electronic components connected to the engine causing misfiring and seizing. The issue is quite prevalent via internet research as potentially thousands of owners with my engine (M278) all experience the same issue. Mercedes Benz advises a $11,000 temporary fix by replacing all engine electronic components but the problem will occur again since the root cause of the oil leak is unknown. Be advised that this is NOT a normal wear and tear issue. This is a design flaw of the engine that placed these components in locations predisposed to contact with engine oil. The root cause of the oil leak is unknown and even Mercedes Benz can not tell why the oil is leaking on these components. If this issue is so prevalent with thousands of owners with the M278 engine in the GL450's, as evidenced by internet searches via Mercedes Benz fan sites, why has no service bulletin or recall been instituted? I am sure your agency can discover numerous examples of this same issue by researching service tickets from Mercedes Benz service centers nation wide. An $11,000 fix is not routine maintenance and Mercedes Benz should be made to fix this prevalent issue via a recall or a service bulletin.

NHTSA ODI 11418207

Dec 22, 2014Transmission & drivetrain

TL* THE CONTACT OWNS A 2014 MERCEDES BENZ GL450. THE CONTACT STATED THAT THE TRANSMISSION JERKED AND HESITATED TO SHIFT. THE FAILURE OCCURRED NUMEROUS TIMES. THE VEHICLE WAS TAKEN TO THE DEALER SEVERAL TIMES. THE TECHNICIAN REPROGRAMMED THE TRANSMISSION SOFTWARE AND THE MODULE WAS REPLACED; HOWEVER, THE FAILURE PERSISTED. THE MANUFACTURER WAS MADE AWARE OF THE FAILURE. THE FAILURE MILEAGE WAS 30.

NHTSA ODI 10667575

Working with the data? Download all 38 complaints as CSV · fetched from NHTSA July 26, 2026

How to use these: a complaint is one owner’s report, filed voluntarily and published unverified. Patterns matter more than any single story. If several owners describe the same failure at similar mileage, put that system at the top of your pre-purchase inspection list. Back to the full 2014 Mercedes-benz Gl-class verdict →