Used car guide

2021 BMW M340D: common problems and MOT failures

What MOT testers find on the BMW M340D first registered in 2021: we looked at the 2,888 MOTs these cars had during 2023–2025. Plus known faults and what to look at before you buy one.

2,888MOTs of 2021 cars, done in 2023–2025
88%pass first time (all 2021 cars: 87%)
11,600typical miles a year
9.7×the usual rate for engine oil leaks

What goes wrong more than usual on a 2021 BMW M340D?

Parts flagged at MOT more often on the 2021 BMW M340D than on all cars registered in 2021.

  • Engine oil leaks9.7× usual
    BMW M340D
    2.9% All 2021 cars
    0.3%

    Failed outright at MOT: 0.2%, against 0% of all 2021 cars. The rest were advisories or minor defects.

    Rough price £80–£600 our estimate

    At the viewing: Look under the engine and where the car is usually parked for fresh oil. Ask whether the leak has been looked at.

Better than most

Brake discs: 1% here, against 6% of all 2021 cars. Brake pads: 1.7% here, against 6.1% of all 2021 cars.

Common 2021 BMW M340D MOT failures and advisories

The share of 2021 BMW M340D MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

  • Tyres
    19% 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.

  • Oil and fluid leaks
    4% 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.

  • Brakes
    3% 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.

  • Wipers, windscreen and mirrors
    3% of testsRough price £15–£250

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

  • Lights and electrics
    2% 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
    2% 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.

Questions to ask the seller before buying a 2021 BMW M340D

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

  1. Any recent work on the engine oil leaks? (Flagged at MOT 9.7× as often on the 2021 BMW M340D as on other cars the same age.)
  2. Can I see the service history and receipts for any big jobs?

Looking at a BMW M340D?

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 BMW M340D compared

YearMOT testsMost flagged
2022900Tyres 19%
2020785Tyres 19%

Where this comes from: the DVSA's anonymised results for every MOT test done in Great Britain during 2023–2025, counting the MOTs of BMW M340D cars first registered in 2021. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score