Mercedes-Benz C 200d
Smaller displacement variant of the OM651. Same technology as the 2.1L but less torque. Known for injector seal issues and timing chain stretch.
Base Diesel with Dignity
100 kW CDI in the W205 — just about adequate. Long distances work, tight overtaking manoeuvres become tiring.
Engine Weaknesses 5
Quality issues with Delphi piezo injectors in the 220 CDI and 250 CDI: injectors fail prematurely. A service action replaced piezo injectors with solenoid injectors free of charge.
Symptoms: Strong vibrations under acceleration, rough running, elevated fuel consumption, exhaust smoke
The OM651 chain tensioner can fail and allow engine oil to escape. Mainly affects vehicles built February–November 2014 (recall). Simplex roller chain increases wear risk.
Symptoms: Light rattling on cold start from the rear of the engine, oil loss, engine warning light
The DPF on the OM651DE18 does not regenerate completely during pure short-trip driving and blocks. A motorway run at least every 2 weeks is required.
Symptoms: DPF warning light, power reduction, engine oil diluted by unburnt fuel
The O-rings on the oil filter housing and oil cooler of the OM651 shrink and develop leaks. Oil seeps out on the side of the engine. Requires removal of the poly-V belt and AC compressor.
Symptoms: Oil spots under the engine, dropping oil level without visible leak, oil smell after driving
The OM651 EGR valve tends to heavy carbonisation on short trips, causing power loss and increased emissions.
Symptoms: Power loss, limp mode, black smoke, EGR fault code, rough idle
Vehicle Weaknesses 7
Longitudinal members, jack-point attachment holes and rear axle subframe rust through. MB offers goodwill replacement.
Polycarbonate blind cover of the panoramic roof incorrectly bonded. When opening, the blind can come loose. Recalled by MB.
Ball joints on the wheel-side wishbone and rubber-metal bushes wear. New suspension geometry makes repairs more involved.
Some W205 models discharge the battery unusually quickly during extended parking. Cause: elevated quiescent current draw from control units.
The W205 shows above-average front axle issues from the second MOT onwards according to TÜV statistics. Worn control arms and drop links are the main causes.
W205 A/C fails with 'Air conditioning off' without a fault code in the onboard computer. Often the compressor or A/C control unit is defective.
Panoramic roof on the W205 creaks when opening and closing. Guide linkage can bend and jam the roof. Repair often requires complete removal.