IsItAGoodCar

Common Problems with the
2014–2018 Mercedes-Benz C-Class (W205)

We've identified 3 known issues that can affect the 2014–2018 Mercedes-Benz C-Class (W205). 1 of these are serious faults that could be expensive to repair.

3
Known Issues
1
Serious
2
Moderate
0
Minor

The 2014–2018 period has 1 more issue than the Mercedes-Benz C-Class (W205) average across all year periods.

All Known Issues

Airmatic air suspension leaks

SeriousSuspension & Chassis

Cars equipped with Airmatic can develop leaking air springs or a failing compressor, causing the car to sag overnight. Ignoring it burns out the compressor, pushing bills toward £2,000+.

Most affected: Models with Airmatic suspension

Estimated cost: £800–£2,000Affects: 2014–2021Often appears around: 60,000–120,000 miles

Typical symptoms

  • •Car sits low after standing overnight
  • •Suspension malfunction warning
  • •Compressor running frequently

What to inspect before you buy

  • ✓Check the car sits level after overnight stand
  • ✓Listen for compressor noise
  • ✓Inspect for recent Airmatic invoices

OM651 Diesel Chain Tensioner Oil Leak

ModerateEngine

The timing chain tensioner gasket can leak oil. If left unaddressed, the loss of tensioner pressure can cause timing chain rattle and eventual stretch.

Most affected: C 220 d, C 250 d

Estimated cost: £200–£500Affects: 2014–2018Often appears around: 50,000–90,000 miles

Typical symptoms

  • •Oil leaking from the right side of the engine
  • •Burning oil smell
  • •Cold start rattle

What to inspect before you buy

  • ✓Inspect the tensioner area for fresh oil
  • ✓Listen for chain rattle on cold start

NOx sensor and AdBlue system faults

ModerateExhaust & Emissions

Common on OM651 and OM654 diesels. Water ingress or soot can kill the sensors. Often requires replacing both upstream and downstream sensors simultaneously.

Most affected: C 220 d, C 250 d, C 300 d

Estimated cost: £600–£1,500Affects: 2014–2021

Typical symptoms

  • •Engine management light
  • •AdBlue countdown
  • •Limp mode

What to inspect before you buy

  • ✓Evidence of NOx sensor pair replacement
  • ✓Ask if the car has had the BlueTEC software update

Buying Tips for the 2014 Mercedes-Benz C-Class (W205)

  • ✓Scan for NOx and AdBlue faults on diesels; Mercedes often requires both sensors to be replaced as a pair.
  • ✓Check Airmatic cars for sinking after an overnight stand.
  • ✓Look for screen delamination on earlier models.
2019–2021 Mercedes-Benz C-Class (W205)

Browse 2014–2018 Mercedes-Benz C-Class (W205) in our Directory

View MOT history, registration data, and reliability scores for 2014–2018 Mercedes-Benz C-Class (W205) vehicles.

View 2014–2018 Directory

Other Mercedes-Benz C-Class (W205) Year Periods

2014–20182019–2021

Looking at a specific 2014 Mercedes-Benz C-Class (W205)?

Enter the registration number to check its full MOT history, outstanding finance, write-off status, and more.

Free Vehicle Check