2021 Mercedes-Benz G-Class diesel: common problems and MOT failures
What MOT testers find on the diesel Mercedes-Benz G-Class first registered in 2021 (diesel cars only): we looked at the 370 MOTs these cars had during 2023–2025. Plus known faults and what to look at before you buy one.
Small sample: there were only 370 MOTs of these cars during 2023–2025, so treat the percentages as rough. The known faults below don't depend on it.
Common 2021 Mercedes-Benz G-Class diesel MOT failures and advisories
The share of 2021 Mercedes-Benz G-Class diesel MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.
- Tyres17% 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.
- Brakes10% 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 electrics2% of testsRough price £10–£80
At the viewing: Ask a friend to check every light, including brake lights and indicators, while you operate them.
- Seats and seatbelts2% of testsRough price £80–£250
At the viewing: Pull each seatbelt sharply. It should lock, and retract cleanly.
- Wipers, windscreen and mirrors2% of testsRough price £15–£250
At the viewing: Check for chips in the driver's view, and test the wipers and washers.
- Suspension1% 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 Mercedes-Benz G-Class diesel
Ask before you travel to see it. A seller who knows the car will have answers, and receipts.
- Can I see the service history and receipts for any big jobs?
Looking at a Mercedes-Benz G-Class?
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Other years
Every year of the Mercedes-Benz G-Class compared
| Year | MOT tests | Most 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 |
| 2022 | 452 | Tyres 16% |
| 2020 | 1,163 | Tyres 14% |
| 2019 | 1,419 | Tyres 16% |
| 2018 | 763 | Tyres 16% |
| 2017 | 690 | Tyres 17% |
| 2016 | 508 | Tyres 18% |
| 2015 | 436 | Brakes 17% |
| 2014 | 352 | Brakes 17% |
| 2013 | 318 | Brakes 17% |
| 2012 | 172 | Brakes 20% |
| 2011 | 129 | Brakes 18% |
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 G-Class cars first registered in 2021. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score