Used car guide

2014 Mercedes-Benz S-Class diesel: common problems and MOT failures

What MOT testers find on the diesel Mercedes-Benz S-Class first registered in 2014 (diesel cars only): we looked at the 3,566 MOTs these cars had during 2023–2025. Plus known faults and what to look at before you buy one.

3,566MOTs of 2014 diesel cars, done in 2023–2025
86%pass first time (all 2014 cars: 70%)
9,200typical miles a year
2.3×the usual rate for ball joint

What goes wrong more than usual on a 2014 Mercedes-Benz S-Class diesel?

Parts flagged at MOT more often on the 2014 Mercedes-Benz S-Class diesel than on all cars registered in 2014.

  • Ball joint2.3× usual
    Mercedes-Benz S-Class
    8.1% All 2014 cars
    3.6%

    Failed outright at MOT: 2.4%, against 2% of all 2014 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.

Better than most

Tyre condition: 6.5% here, against 13.5% of all 2014 cars. Suspension arm bushes and joints: 1.2% here, against 7% of all 2014 cars.

Common 2014 Mercedes-Benz S-Class diesel MOT failures and advisories

The share of 2014 Mercedes-Benz S-Class diesel MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

  • Tyres
    23% 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
    15% 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
    11% 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
    5% 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
    5% 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
    2% 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.

Questions to ask the seller before buying a 2014 Mercedes-Benz S-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 ball joint? (Flagged at MOT 2.3× as often on the 2014 Mercedes-Benz S-Class diesel as on other cars the same age.)
  2. Can I see the service history and receipts for any big jobs?

Looking at a Mercedes-Benz S-Class?

Check the actual car: its own MOT history, mileage and what to ask the seller. Free, no sign-up.

Other years

Every year of the Mercedes-Benz S-Class compared

YearMOT testsMost flagged
2026–Too new for MOT data
2025–Too new for MOT data
2024–Too new for MOT data
2023513Tyres 14%
2022651Tyres 12%
2021148Tyres 20%
2020775Tyres 21%
20196,969Tyres 19%
20186,939Tyres 18%
20177,115Tyres 22%
20168,055Tyres 23%
20156,498Tyres 23%
20132,929Brakes 26%
20123,634Brakes 31%
20112,761Brakes 30%
20102,549Brakes 31%
20092,529Brakes 37%
20082,858Brakes 39%
20073,814Brakes 40%
20063,082Brakes 37%
20051,569Brakes 37%
20041,856Brakes 37%
20031,931Brakes 35%
20021,143Brakes 33%
20011,009Brakes 34%
2000748Suspension 35%
1999491Brakes 34%
1998501Brakes 32%
1997351Brakes 34%
1996318Brakes 28%
1995257Suspension 40%
1994148Suspension 31%
1993–Too few tests
1991133Brakes 18%
1990128Suspension 27%

Where this comes from: the DVSA's anonymised results for every MOT test done in Great Britain during 2023–2025, counting the MOTs of Mercedes-Benz S-Class cars first registered in 2014. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score