Mercedes-Benz GLC 300de
Development of the OM654 with 48V mild hybrid and integrated starter-generator. Clean and economical. Too new on the market for known weaknesses to have emerged.
Diesel Sovereign
Strong diesel with 246 kW. Enormous torque for effortless progress, but not a fun engine.
Engine Weaknesses 5
Recall action code 2090008: the electric coolant pump can develop an internal leak. Coolant enters the vacuum circuit and increases fire risk. Mercedes replaces the solenoid valve and applies a software update.
Symptoms: Coolant loss without visible external leak, warning message on instrument cluster, in the worst case smoke development
The OM654M combines the vacuum pump and oil pump in a tandem unit. If coolant enters the pump via the vacuum circuit the oil supply can fail. Replacement requires gearbox removal.
Symptoms: Oil pressure warning, engine noises from oil starvation, in the worst case engine failure without prior warning
As an updated OM654 variant the OM654M carries the rocker arm/camshaft wear risk of the base OM654. Whether the revision fully resolves the issue remains to be seen.
Symptoms: Ticking noise from valve cover area, misfires, engine warning light
The OM654M DPF requires adequate motorway driving for regeneration. Purely urban use leads to oil dilution and premature DPF blockage.
Symptoms: DPF warning light, engine oil level rising from fuel ingress, power reduction
The OM654M as a high-output diesel is often used in city traffic. On short trips under 15 km the DPF cannot reach the necessary regeneration temperature.
Symptoms: DPF warning symbol, frequent regeneration requests, power reduction, slightly elevated oil level from fuel dilution
Vehicle Weaknesses 11
A software fault in the engine management incorrectly detects misfires and cuts the fuel injection. Approximately 60,000 vehicles affected.
Inadequate attachment of the acoustic pad in the B-pillar. The pad can detach and impair the seat belt retractor. Belt could fail in an accident.
Acoustic pads on the B-pillar can detach and jam the seat belt retractor, preventing the pretensioner from deploying. 908 vehicles affected.
Faulty parking sensors and camera systems trigger false warnings. In snowfall, the emergency brake assist activates unintentionally.
The MBUX system freezes or becomes unresponsive. Assistance systems can be permanently deactivated. OTA updates often only temporarily relieve the symptoms.
The C254 also develops noises at the front axle when turning. Ball joints and strut top mounts wear faster with larger wheels.
MBUX system shows sporadic crashes, sluggish responses and connection drops, especially in early production months. Software updates at the workshop frequently needed.
Park assist detects non-existent obstacles, brake assist brakes without reason in snowfall, blind spot monitor fails. False alarms can trigger dangerous situations.
The MBUX system gets very hot on longer journeys. The display shows visual noise or goes black in heat. The fault disappears after cooling down.
Early C254 models show software faults: rear camera stays black, driver assistance fails, screen freezes. Usually resolvable after OTA updates.
Rattling passenger door on cobblestones, creaking centre console above 60 km/h, vibrations in the accelerator pedal. Ambient lighting elements detach.
Reports & Tests
11 owner complaints filed with NHTSA (2022–2025). Most reported: Electrical (8), Collision Avoidance (3), Seats (2).