Used car guide

2009 Mercedes-Benz B-Class: common problems and what to check

What gets flagged at MOT on 2009 Mercedes-Benz B-Classs, from 3,989 tests in 2025, plus known faults and what to look at before you buy one.

3,989MOT tests in 2025
58%pass first time (all 2009 cars: 58%)
6,000typical miles a year
3.5×the usual rate for rigid brake pipes

What stands out

Parts flagged at MOT more often on 2009 Mercedes-Benz B-Classs than on all cars registered in 2009.

  • Rigid brake pipes3.5× usual
    Mercedes-Benz B-Class
    26.4% All 2009 cars
    7.5%

    Failed outright at MOT: 4.4%, against 1.2% of all 2009 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.

  • Drive shaft (CV) joints2.9× usual
    Mercedes-Benz B-Class
    15.3% All 2009 cars
    5.3%

    Failed outright at MOT: 6.4%, against 2.4% of all 2009 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.

  • Corroded fuel pipes8.2× usual
    Mercedes-Benz B-Class
    4.9% All 2009 cars
    0.6%

    Failed outright at MOT: 0%, against 0% of all 2009 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 covers2.2× usual
    Mercedes-Benz B-Class
    6.9% All 2009 cars
    3.1%

    Failed outright at MOT: 3.3%, against 1.8% of all 2009 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.

  • Side repeaters3× usual
    Mercedes-Benz B-Class
    4.5% All 2009 cars
    1.5%

    Failed outright at MOT: 3.4%, against 0.9% of all 2009 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.

Better than most

Suspension arm bushes and joints: 2.1% here, against 11.1% of all 2009 cars. Engine oil leaks: 2.7% here, against 10.4% of all 2009 cars.

By area

The share of 2009 Mercedes-Benz B-Class MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

  • Brakes
    48% 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
    38% 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
    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.

  • Lights and electrics
    27% 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
    15% 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
    10% of testsRough price £15–£250

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

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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%
20125,658Tyres 32%
20113,373Brakes 42%
20104,279Brakes 44%
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 2009 Mercedes-Benz B-Classs registered in 2009. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score