Used car guide

2012 Mercedes-Benz B-Class: common problems and what to check

What gets flagged at MOT on 2012 Mercedes-Benz B-Classs, from 5,658 tests in 2025, plus known faults and what to look at before you buy one.

5,658MOT tests in 2025
69%pass first time (all 2012 cars: 63%)
6,600typical miles a year
2.3×the usual rate for rigid brake pipes

What stands out

Parts flagged at MOT more often on 2012 Mercedes-Benz B-Classs than on all cars registered in 2012.

  • Rigid brake pipes2.3× usual
    Mercedes-Benz B-Class
    12.9% All 2012 cars
    5.5%

    Failed outright at MOT: 2.7%, 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.

  • Link ball joint covers3.4× usual
    Mercedes-Benz B-Class
    8.4% All 2012 cars
    2.5%

    Failed outright at MOT: 4.2%, against 1.4% 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.

  • Engine warning light2× usual
    Mercedes-Benz B-Class
    3.6% All 2012 cars
    1.8%

    Failed outright at MOT: 3.6%, against 1.8% of all 2012 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.

Better than most

Suspension arm bushes and joints: 1.1% here, against 10.1% of all 2012 cars. Shock absorbers: 1% here, against 6.5% of all 2012 cars.

By area

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

  • Tyres
    32% 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
    30% 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
    28% 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
    16% 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
    7% of testsRough price £15–£250

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

  • Oil and fluid leaks
    3% 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.

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Other years

YearMOT testsMost flagged
2019599Tyres 25%
20183,892Tyres 31%
20175,689Tyres 29%
20165,353Tyres 31%
20155,654Tyres 32%
20148,185Tyres 32%
20136,957Tyres 33%
20113,373Brakes 42%
20104,279Brakes 44%
20093,989Brakes 48%
20083,072Brakes 51%
20072,249Brakes 47%
20061,611Brakes 51%

Where this comes from: the DVSA's anonymised results for every MOT test in Great Britain in 2025, counting tests of 2012 Mercedes-Benz B-Classs registered in 2012. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score