2010 Mercedes-Benz S-Class diesel: common problems and MOT failures

What goes wrong more than usual on a 2010 Mercedes-Benz S-Class diesel?

Parts flagged at MOT more often on the 2010 Mercedes-Benz S-Class diesel than on all cars registered in 2010.

• Rigid brake pipes2.2× usual
  Mercedes-Benz S-Class

  14.4% All 2010 cars

  6.5%

  Failed outright at MOT: 2.1%, against 1.1% of all 2010 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 bearings3.5× usual
  Mercedes-Benz S-Class

  6.6% All 2010 cars

  1.9%

  Failed outright at MOT: 0.7%, against 0.8% of all 2010 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.

• Ball joint1.8× usual
  Mercedes-Benz S-Class

  10.9% All 2010 cars

  6.2%

  Failed outright at MOT: 3.9%, against 3.3% of all 2010 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.

• Flexible couplings27× usual
  Mercedes-Benz S-Class

  2.7% All 2010 cars

  0.1%

  Failed outright at MOT: 0.1%, against 0% of all 2010 cars. The rest were advisories or minor defects.

  Rough price £150–£1,000 our estimate

  At the viewing: Check the sills, wheel arches and underneath for rust, and look along the panels for uneven gaps or paint.

• Diesel smoke emissions2.6× usual
  Mercedes-Benz S-Class

  2.3% All 2010 cars

  0.9%

  Failed outright at MOT: 2.1%, against 0.8% of all 2010 cars. The rest were advisories or minor defects.

  Rough price £175–£900 (catalytic converter) ClickMechanic

  At the viewing: Look for smoke when revving the warm engine and for engine or DPF warning lights.

Common 2010 Mercedes-Benz S-Class diesel MOT failures and advisories

The share of 2010 Mercedes-Benz S-Class diesel MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

• Brakes
  33% 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
  27% 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
  22% 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
  15% 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
  9% 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
  6% 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 2010 Mercedes-Benz S-Class 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 2.2× as often on the 2010 Mercedes-Benz S-Class diesel as on other cars the same age.)
2. Any recent work on the wheel bearings? (Flagged at MOT 3.5× as often on the 2010 Mercedes-Benz S-Class diesel as on other cars the same age.)
3. Any recent work on the ball joint? (Flagged at MOT 1.8× as often on the 2010 Mercedes-Benz S-Class diesel as on other cars the same age.)
4. Can I see the service history and receipts for any big jobs?