2006 Mercedes-Benz B-Class diesel: common problems and MOT failures

What goes wrong more than usual on a 2006 Mercedes-Benz B-Class diesel?

Parts flagged at MOT more often on the 2006 Mercedes-Benz B-Class diesel than on all cars registered in 2006.

• Drive shaft (CV) joints3.3× usual
  Mercedes-Benz B-Class

  24.2% All 2006 cars

  7.3%

  Failed outright at MOT: 12.3%, against 3.3% of all 2006 cars. The rest were advisories or minor defects.

  Rough price £60–£350 our estimate

  At the viewing: Drive slowly on full steering lock in both directions and listen for clicking. Look for split rubber boots behind the front wheels.

• Rigid brake pipes2.1× usual
  Mercedes-Benz B-Class

  29.5% All 2006 cars

  14%

  Failed outright at MOT: 4.8%, against 2.5% of all 2006 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.

• Corroded fuel pipes7.9× usual
  Mercedes-Benz B-Class

  5.5% All 2006 cars

  0.7%

  Failed outright at MOT: 0%, against 0% of all 2006 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.

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

  7.5% All 2006 cars

  3.7%

  Failed outright at MOT: 3.7%, against 1.7% of all 2006 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.

• Diesel smoke emissions4.8× usual
  Mercedes-Benz B-Class

  4.3% All 2006 cars

  0.9%

  Failed outright at MOT: 4.1%, against 0.8% of all 2006 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 2006 Mercedes-Benz B-Class diesel MOT failures and advisories

The share of 2006 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
  56% 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.

• Suspension
  39% 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.

• Tyres
  34% 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.

• Lights and electrics
  33% of testsRough price £10–£80

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

• Driveshafts and joints
  24% of testsRough price £60–£350

  At the viewing: On full steering lock, drive slowly and listen for clicking from the front wheels.

• Wipers, windscreen and mirrors
  13% 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 2006 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 drive shaft (cv) joints? (Flagged at MOT 3.3× as often on the 2006 Mercedes-Benz B-Class diesel as on other cars the same age.)
2. Any recent work on the rigid brake pipes? (Flagged at MOT 2.1× as often on the 2006 Mercedes-Benz B-Class diesel as on other cars the same age.)
3. Any recent work on the corroded fuel pipes? (Flagged at MOT 7.9× as often on the 2006 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?