Mercedes-Benz C-Class2018

Known issues

• DPF (diesel particulate filter) clogging and regeneration issues, particularly on low-mileage or short-trip driving; can result in limp mode and €800–1,500 repair costs
• EGR valve carbon build-up and sticking, leading to rough idle, reduced power, and potential engine management light
• Diesel injector fouling and common-rail pressure sensor faults, causing difficult cold starts and white smoke
• Transmission fluid leaks from the 7-speed automatic gearbox; relatively minor but requires seal replacement
• AdBlue system faults and NOx sensor degradation; reduced performance and warning lights if not addressed
• Timing chain rattle on cold start (Mercedes M270/M274 petrol engines, not diesel; OM651 diesel is generally chain-driven and more reliable in this regard)

Good for

• Fuel economy and range on the motorway; real-world combined economy around 45–50 mpg with careful driving
• Refined NVH (noise, vibration, harshness); cabin is quiet and comfortable for long journeys
• Solid build quality, interior materials, and German engineering; feels premium for the class
• Strong resale value and parts availability through independent specialists and used breakers