Used car guide

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

What gets flagged at MOT on 2012 Mercedes-Benz S-Classs, from 1,148 tests in 2025, plus known faults and what to look at before you buy one.

1,148MOT tests in 2025
80%pass first time (all 2012 cars: 63%)
7,700typical miles a year
2.6×the usual rate for rigid brake pipes

What stands out

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

  • Rigid brake pipes2.6× usual
    Mercedes-Benz S-Class
    14.1% All 2012 cars
    5.5%

    Failed outright at MOT: 1.2%, 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.

  • Wheel bearings5.4× usual
    Mercedes-Benz S-Class
    8.1% All 2012 cars
    1.5%

    Failed outright at MOT: 0.3%, against 0.6% of all 2012 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 joint2× usual
    Mercedes-Benz S-Class
    11.1% All 2012 cars
    5.6%

    Failed outright at MOT: 3.3%, against 3% 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 light2.9× usual
    Mercedes-Benz S-Class
    5.2% All 2012 cars
    1.8%

    Failed outright at MOT: 5.2%, 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: 4.7% here, against 10.1% of all 2012 cars. Braking performance: 2.2% here, against 4.9% of all 2012 cars.

By area

The share of 2012 Mercedes-Benz S-Class 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
    26% 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
    21% 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
    14% 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
    10% 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.

Looking at a Mercedes-Benz S-Class?

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Other years

YearMOT testsMost flagged
20192,195Tyres 19%
20182,177Tyres 19%
20172,265Tyres 21%
20162,634Tyres 24%
20152,124Tyres 23%
20141,572Tyres 21%
2013946Brakes 27%
2011883Brakes 32%
2010773Brakes 32%
2009753Brakes 37%
2008810Brakes 40%
20071,127Brakes 39%
2006883Brakes 38%
2004521Brakes 35%
2003522Brakes 34%

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