2011 Mercedes-Benz B-Class diesel: common problems and MOT failures

What goes wrong more than usual on a 2011 Mercedes-Benz B-Class diesel?

Parts flagged at MOT more often on the 2011 Mercedes-Benz B-Class diesel than on all cars registered in 2011.

• Rigid brake pipes3.9× usual
  Mercedes-Benz B-Class

  22% All 2011 cars

  5.7%

  Failed outright at MOT: 3.7%, against 1% of all 2011 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.

• Side repeaters6.5× usual
  Mercedes-Benz B-Class

  7.8% All 2011 cars

  1.2%

  Failed outright at MOT: 6.5%, against 0.8% of all 2011 cars. The rest were advisories or minor defects.

  Rough price £10–£80 our estimate

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

• Individual direction indicators2.8× usual
  Mercedes-Benz B-Class

  8.5% All 2011 cars

  3%

  Failed outright at MOT: 4%, against 1.2% of all 2011 cars. The rest were advisories or minor defects.

  Rough price £10–£80 our estimate

  At the viewing: Ask a friend to check every light while you work the switches: indicators, brake lights, fog lights and reversing lights.

• Shock absorbers1.8× usual
  Mercedes-Benz B-Class

  12.5% All 2011 cars

  7%

  Failed outright at MOT: 3.4%, against 1.8% of all 2011 cars. The rest were advisories or minor defects.

  Rough price £200–£300 (pair, average rear to front) ClickMechanic

  At the viewing: Push down hard on each corner. It should bounce once and settle. Look for oil on the shock absorber body.

• Corroded fuel pipes13.7× usual
  Mercedes-Benz B-Class

  4.1% All 2011 cars

  0.3%

  Failed outright at MOT: 0%, against 0% of all 2011 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.

Common 2011 Mercedes-Benz B-Class diesel MOT failures and advisories

The share of 2011 Mercedes-Benz B-Class diesel MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

• Brakes
  44% 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
  35% 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
  34% 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
  30% of testsRough price £10–£80

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

• Wipers, windscreen and mirrors
  9% of testsRough price £15–£250

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

• Steering
  6% of testsRough price £100–£450

  At the viewing: On a straight road the steering wheel should sit straight. Feel for play or knocking when turning.

Questions to ask the seller before buying a 2011 Mercedes-Benz B-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 3.9× as often on the 2011 Mercedes-Benz B-Class diesel as on other cars the same age.)
2. Any recent work on the side repeaters? (Flagged at MOT 6.5× as often on the 2011 Mercedes-Benz B-Class diesel as on other cars the same age.)
3. Any recent work on the individual direction indicators? (Flagged at MOT 2.8× as often on the 2011 Mercedes-Benz B-Class diesel as on other cars the same age.)
4. Can I see the service history and receipts for any big jobs?