Mercedes C-Class W205 (2014-2021): known problems and buying guide

Before you buy

1. Air suspension: Park the car overnight and check whether a corner sinks. A scanner reads the level sensors and fault memory. Bad result: a low corner, a compressor that runs all the time, or cockpit warnings.
2. Timing chain: On M274 petrol engines, listen for a metallic rattle on cold start and look for oil stains. A scanner reads stored timing faults. Bad result: a rattle that lasts several seconds, or stored faults.
3. Engine fire recall: On OM654 diesels built 2017-2021, check the coolant recall by VIN with a Mercedes dealer. Bad result: an open campaign or coolant loss.
4. Front axle: On a lift, check the ball joints and axle mounts for play. Drive over bumps and listen. Bad result: play in a joint, or knocking from the front.
5. Steering coupling: Ask a Mercedes dealer to confirm the steering coupling lock by VIN. The check is free. Bad result: an open campaign, or noise and steering problems on the test drive.
6. Infotainment: Test every screen, the touchpad and the voice control. A scanner shows the software version. Bad result: freezes, reboots or a dead touchpad.
7. Rear drains: Check the drains at the rear window and sunroof, and the rear footwell for damp. Bad result: damp in the footwell or warnings from the electrics.
8. 12 V battery: Test the battery after the car has stood. Use a battery tester. Bad result: low voltage, or start-stop that stays off.