The Mercedes-Benz faults that actually come through the workshop door — what causes them, the order to test in, and what an honest independent garage should charge.
These are the Mercedes-Benz faults we see most often in the workshop, each with the real cause on Mercedes-Benz engines, the order to test in, and an honest independent-garage cost rather than a dealer estimate.
Mercedes-Benz problems explained
- Mercedes OM651 Loss of Power — OM651 loss of power is one of the most common Mercedes diesel faults in the UK. Three causes dominate: internal EGR cooler failure (coolant leak into intake), blocked DPF, and faulty Delphi injectors. Diagnose in that order.
Symptoms overlap between makes, but the likely cause does not. Knowing which component fails first on a Mercedes-Benz is what stops good parts being replaced on guesswork — always pay for the diagnosis before you pay for parts.