2021 MG ZS: common problems and what to check
What gets flagged at MOT on 2021 MG ZSs, from 14,989 tests in 2025, plus known faults and what to look at before you buy one.
What stands out
Parts flagged at MOT more often on 2021 MG ZSs than on all cars registered in 2021.
- Brake discs2.4× usualMG ZS17.2% All 2021 cars7.1%
Failed outright at MOT: 1.1%, against 0.3% of all 2021 cars. The rest were advisories or minor defects.
Rough price £150–£350 our estimateAt the viewing: Look through the wheel at the brake disc: a deep lip at the edge or heavy scoring means they're worn. Feel for judder when braking.
- Braking performance3.6× usualMG ZS2.9% All 2021 cars0.8%
Failed outright at MOT: 0.8%, against 0.2% of all 2021 cars. The rest were advisories or minor defects.
Rough price £100–£350 our estimateAt the viewing: On a quiet road, brake firmly from about 30mph. The car should stop straight without pulling.
By area
The share of 2021 MG ZS MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.
- Tyres26% 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.
- Brakes23% 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 electrics7% of testsRough price £10–£80
At the viewing: Ask a friend to check every light, including brake lights and indicators, while you operate them.
- Suspension5% 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 mirrors4% of testsRough price £15–£250
At the viewing: Check for chips in the driver's view, and test the wipers and washers.
- Seats and seatbelts4% of testsRough price £80–£250
At the viewing: Pull each seatbelt sharply. It should lock, and retract cleanly.
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Other years
| Year | MOT tests | Most flagged |
|---|---|---|
| 2023 | 1,644 | Tyres 18% |
| 2022 | 17,647 | Brakes 23% |
| 2020 | 12,499 | Tyres 34% |
| 2019 | 8,696 | Tyres 35% |
| 2018 | 5,092 | Tyres 32% |
Where this comes from: the DVSA's anonymised results for every MOT test in Great Britain in 2025, counting tests of 2021 MG ZSs registered in 2021. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score