Used car guide

2017 Mercedes-Benz B-Class diesel: common problems and MOT failures

What MOT testers find on the diesel Mercedes-Benz B-Class first registered in 2017 (diesel cars only): we looked at the 13,908 MOTs these cars had during 2023–2025. Plus known faults and what to look at before you buy one.

13,908MOTs of 2017 diesel cars, done in 2023–2025
82%pass first time (all 2017 cars: 80%)
6,600typical miles a year
2.4×the usual rate for number plate lights

What goes wrong more than usual on a 2017 Mercedes-Benz B-Class diesel?

Parts flagged at MOT more often on the 2017 Mercedes-Benz B-Class diesel than on all cars registered in 2017.

  • Number plate lights2.4× usual
    Mercedes-Benz B-Class
    4.8% All 2017 cars
    2%

    Failed outright at MOT: 2.9%, against 0.6% of all 2017 cars. The rest were advisories or minor defects.

    Rough price £5–£40 our estimate

    At the viewing: Check the number plate lights work and the plates are clean and legal.

Common 2017 Mercedes-Benz B-Class diesel MOT failures and advisories

The share of 2017 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.

  • Tyres
    31% 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
    18% 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.

  • Lights and electrics
    9% of testsRough price £10–£80

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

  • Suspension
    6% 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.

  • 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.

  • Seats and seatbelts
    3% of testsRough price £80–£250

    At the viewing: Pull each seatbelt sharply. It should lock, and retract cleanly.

Known faults on the 2017 Mercedes-Benz B-Class diesel

Reported by owners, mechanics and buying guides for this model and age. Check which engine the car has, as some apply to one engine only.

Questions to ask the seller before buying a 2017 Mercedes-Benz B-Class diesel

Ask before you travel to see it. A seller who knows the car will have answers, and receipts.

  1. Have all the recalls been done? Can a Mercedes dealer confirm from the VIN?
  2. Any recent work on the number plate lights? (Flagged at MOT 2.4× as often on the 2017 Mercedes-Benz B-Class diesel as on other cars the same age.)
  3. Can I see the service history and receipts for any big jobs?

Looking at a Mercedes-Benz B-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 B-Class compared

YearMOT testsMost flagged
2026–Too new for MOT data
2025–Too new for MOT data
2024–Too new for MOT data
2023–Too new for MOT data
20221,424Tyres 19%
20213,631Tyres 20%
20208,747Tyres 23%
20191,758Tyres 24%
201811,521Tyres 29%
201615,928Tyres 31%
201516,859Tyres 31%
201424,593Tyres 32%
201321,133Tyres 32%
201217,251Tyres 31%
201110,635Brakes 40%
201013,626Brakes 42%
200913,002Brakes 47%
200810,481Brakes 50%
20078,076Brakes 48%
20066,099Brakes 49%
20051,264Brakes 48%

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 B-Class cars first registered in 2017. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score