2021 Mercedes-Benz CLA diesel: common problems and MOT failures

What goes wrong more than usual on a 2021 Mercedes-Benz CLA diesel?

Parts flagged at MOT more often on the 2021 Mercedes-Benz CLA diesel than on all cars registered in 2021.

• Tyre condition1.6× usual
  Mercedes-Benz CLA

  16.7% All 2021 cars

  10.3%

  Failed outright at MOT: 6.1%, against 3.6% of all 2021 cars. The rest were advisories or minor defects.

  Rough price £70–£150 our estimate

  At the viewing: Check the tread on all four tyres, including the inside edges. Uneven wear can point to tracking or suspension problems.

Common 2021 Mercedes-Benz CLA diesel MOT failures and advisories

The share of 2021 Mercedes-Benz CLA diesel MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

• Tyres
  31% of testsRough price £70–£150

  At the viewing: Check the tread on all four tyres, including the inside edges, and look for cracks or bulges.

• Brakes
  13% of testsRough price £150–£350

  At the viewing: Look for a lip on the disc edges and feel for judder or pulling when braking firmly from about 40mph.

• Wipers, windscreen and mirrors
  5% of testsRough price £15–£250

  At the viewing: Check for chips in the driver's view, and test the wipers and washers.

• Lights and electrics
  4% of testsRough price £10–£80

  At the viewing: Ask a friend to check every light, including brake lights and indicators, while you operate them.

• Suspension
  2% of testsRough price £120–£400

  At the viewing: Listen for knocks over speed bumps, and look behind each front wheel for a snapped coil spring.

• Seats and seatbelts
  1% of testsRough price £80–£250

  At the viewing: Pull each seatbelt sharply. It should lock, and retract cleanly.

Known faults on the 2021 Mercedes-Benz CLA diesel

Reported by owners, mechanics and buying guides for this model and age. Check which engine the car has, as some apply to one engine only.

• Seven recalls: airbag, turbo oil line, gearbox, ECU

  Some cars

  Recalls covered a driver's airbag that might not be bolted down, a leaking turbo oil line, a gearbox that might not select Drive or Reverse, an engine ECU contact, radar software, the air con refrigerant and a generator gas line.

  At the viewing: Ask a Mercedes dealer to check the VIN for outstanding recalls.

  Source: What Car?: used Mercedes CLA (2019 on) reliability

Questions to ask the seller before buying a 2021 Mercedes-Benz CLA diesel

Ask before you travel to see it. A seller who knows the car will have answers, and receipts.

1. Have all the recalls been done, especially the airbag and turbo oil line?
2. Any recent work on the tyre condition? (Flagged at MOT 1.6× as often on the 2021 Mercedes-Benz CLA diesel as on other cars the same age.)
3. Can I see the service history and receipts for any big jobs?