2012 Mercedes-Benz CLS diesel: common problems and MOT failures

What goes wrong more than usual on a 2012 Mercedes-Benz CLS diesel?

Parts flagged at MOT more often on the 2012 Mercedes-Benz CLS diesel than on all cars registered in 2012.

• Rigid brake pipes4.3× usual
  Mercedes-Benz CLS

  21.4% All 2012 cars

  5%

  Failed outright at MOT: 3.5%, against 0.8% of all 2012 cars. The rest were advisories or minor defects.

  Rough price £100–£400 our estimate

  At the viewing: Ask to see underneath, or check the MOT advisories: corroded brake or fuel pipes get worse every year and fail the MOT when they do.

• Wheel bearings3.6× usual
  Mercedes-Benz CLS

  5% All 2012 cars

  1.4%

  Failed outright at MOT: 0.1%, against 0.5% of all 2012 cars. The rest were advisories or minor defects.

  Rough price £120–£300 (one bearing) ClickMechanic

  At the viewing: Listen for a hum or growl that changes as you steer at speed.

• Link ball joint covers2.5× usual
  Mercedes-Benz CLS

  4.9% All 2012 cars

  2%

  Failed outright at MOT: 2.2%, against 1.1% of all 2012 cars. The rest were advisories or minor defects.

  Rough price £60–£150 (one joint) ClickMechanic

  At the viewing: Listen for knocking over bumps and check the rubber boots behind the wheels aren't split.

Common 2012 Mercedes-Benz CLS diesel MOT failures and advisories

The share of 2012 Mercedes-Benz CLS diesel MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

• Brakes
  35% 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.

• Tyres
  33% 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.

• Suspension
  24% 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.

• Lights and electrics
  11% of testsRough price £10–£80

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

• Oil and fluid leaks
  6% of testsRough price £80–£600

  At the viewing: Look under the engine and on the ground where the car is usually parked for fresh oil or fluid.

• 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.

Questions to ask the seller before buying a 2012 Mercedes-Benz CLS diesel

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

1. Any recent work on the rigid brake pipes? (Flagged at MOT 4.3× as often on the 2012 Mercedes-Benz CLS diesel as on other cars the same age.)
2. Any recent work on the wheel bearings? (Flagged at MOT 3.6× as often on the 2012 Mercedes-Benz CLS diesel as on other cars the same age.)
3. Any recent work on the link ball joint covers? (Flagged at MOT 2.5× as often on the 2012 Mercedes-Benz CLS diesel as on other cars the same age.)
4. Can I see the service history and receipts for any big jobs?