Mercedes-Benz C-Class Common Faults & Problems (UK Buyer's Guide)
W205 & W206, 2014–2024 · Executive saloon / estate
This is an independent guide to the Mercedes-Benz C-Class, written for used car buyers rather than sellers. The faults below come from owner reports, UK garage patterns and MOT history for this generation — not manufacturer marketing, and we take no commission from any dealer. Use it to spot the expensive problems before you hand over money.
Superb long-distance car, but out-of-warranty electronics and air suspension get costly.
Common Faults
Each fault below is drawn from real owner reports and UK garage patterns for this generation — not generic used-car advice.
Airmatic suspension failure
seriousAir struts and the compressor fail, dropping the car overnight.
Check for: Does it sit level after standing? Listen for the compressor running for a long time.
Typical cost: £800–£1,600 per corner
AdBlue system and NOx sensors on diesels
seriousNOx sensor and AdBlue injector faults are common and will eventually stop the car starting.
Check for: Any AdBlue countdown message.
Typical cost: £500–£1,200
COMAND infotainment and camera faults
minorScreens and reversing cameras drop out, often a connector or software issue.
Check for: Test every screen function and the 360 camera if fitted.
Typical cost: £300–£900
What to Check Before Buying
Take this list to the viewing. Every point comes straight from the faults above.
- Airmatic suspension failure: Does it sit level after standing? Listen for the compressor running for a long time.
- AdBlue system and NOx sensors on diesels: Any AdBlue countdown message.
- COMAND infotainment and camera faults: Test every screen function and the 360 camera if fitted.
MOT history red flags
If any of these appear on the last two MOTs, negotiate hard or walk away.
- Emissions failure on a diesel
- Suspension advisories mentioning ride height
Sharp questions to ask the seller
- Any AdBlue or emissions warnings in the last year?
- Is the air suspension original?
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