1,362 tests in 2025
Mazda B reliability and MOT pass rate
66.7% passed first time. The 33.3% fail rate is 10.7 points worse than the all-car average, on a median example 22 years old with 118,573 miles.
Pass rate
66.7%
22.6% of all cars failed; 33.3% of these did.
Fixed on the day
7.2%
Passed after a defect was put right during the visit.
Median at test
118,573 mi
22 years old.
Fail rate by age
| Age at test | Tests | Fail rate |
|---|---|---|
| 3-5 years | 0 | — |
| 6-9 years | 3 | — |
| 10-13 years | 0 | — |
| 14+ years | 1,359 | 33.3% |
What the B fails on
Share of failed tests with at least one fail item in each DVSA inspection section. A test can fail in several sections at once.
- Lamps, reflectors and electrical equipment12 dangerous50.3%
- Body, chassis, structure24 dangerous49.4%
- Brakes58 dangerous38.9%
- Suspension40 dangerous36.2%
- Visibility17.2%
- Tyres76 dangerous13.9%
- Noise, emissions and leaks3 dangerous13.2%
- Steering3 dangerous11.3%
Is the B getting worse?
The fail rate fell 0.7 points to 33.3% from 2022 to 2025 while the median one tested aged 3 years, which is about what ageing alone predicts (-1.2 points). Read it as the fleet getting older rather than the model changing.
| Year | Tests | Median age | Fail rate | All cars | |
|---|---|---|---|---|---|
| 2022 | 2,179 | 19 | 34% | 22.5% | |
| 2023 | 1,874 | 20 | 34.6% | 22.8% | |
| 2024 | 1,474 | 21 | 33.7% | 23.2% | |
| 2025 | 1,358 | 22 | 33.3% | 22.6% |
Fail rate is first attempts at class 4 tests. Median age is the age of a typical B at its test that year, and it is the number to watch: across the whole fleet each extra year of age adds roughly 1.9 points to the fail rate, so a model whose age and fail rate rise together is simply getting older.
The exact defects that fail it
Every failure item DVSA recorded against a B in 2025, counted by how many tests each one appeared on.
- 1Rear fog lamp: not working89 tests
- 2Joints: constant velocity boot split or insecure, no longer prevents the ingress of dirt71 tests
- 3Chassis condition: or chassis has excessive corrosion, seriously affecting its strength within 30cm of a body mounting68 tests
- 4Rigid brake pipes: excessively corroded55 tests
- 5Position lamp: not working46 tests
- 6Wipers: does not clear the windscreen effectively46 tests
- 7Component mounting prescribed areas: prescribed area excessively corroded significantly reducing structural strength40 tests
- 8Tread depth: tread depth below requirements of 1.6mm36 tests
What wears out first
Advisories are the tester flagging wear that is still legal. A typical B collects 3.71 of them per test, and these are the ones that come up most. Treat it as the running-repairs list for the next year or two.
- 1Rigid brake pipes: excessively corroded324 tests
- 2Chassis condition: corroded to the extent that the rigidity of the assembly is significantly reduced162 tests
- 3Tread depth: tread depth below requirements of 1.6mm161 tests
- 4Engine oil leaks: leaking excessively from engine134 tests
- 5Registration plates: inscription illegible111 tests
- 6Chassis condition: or chassis has excessive corrosion, seriously affecting its strength within 30cm of a body mounting106 tests
- 7Condition: has a tear, caused by separation or partial failure of its structure102 tests
- 8Wheel bearings: has excessive play100 tests
Questions
What is the Mazda B MOT pass rate?
66.7% of the 1,362 Mazda B first-attempt MOTs in 2025 passed. The fail rate of 33.3% compares with 22.6% across all cars. A further 7.2% passed after a defect was fixed during the test visit.
What does a Mazda B usually fail on?
The single most common failure is "Rear fog lamp: not working", recorded on 89 failed tests, followed by "Joints: constant velocity boot split or insecure, no longer prevents the ingress of dirt" and "Chassis condition: or chassis has excessive corrosion, seriously affecting its strength within 30cm of a body mounting". By section, lamps, reflectors and electrical equipment appears in 50.3% of failures, body, chassis, structure appears in 49.4% of failures, brakes appears in 38.9% of failures.
Does age change the odds?
Sharply. At 3 to 5 years old the fail rate was n/a%; at 14+ years it was 33.3%. The median Mazda B tested in 2025 was 22 years old with 118,573 miles.
Is the Mazda B getting less reliable?
The fail rate fell 0.7 points to 33.3% from 2022 to 2025 while the median one tested aged 3 years, which is about what ageing alone predicts (-1.2 points). Read it as the fleet getting older rather than the model changing.
First-attempt class 4 tests, 2025, from DVSA’s anonymised MOT data (OGL v3, retrieved 2026-09-12). DVSA records newer cars trim by trim; this page adds every B trim together. Year-on-year figures come from the same DVSA extracts for 2026 and earlier years. Full method on the pass rates hub.
Other Mazda models
Checking a particular B?
The odds above are the model. The car in front of you has its own record: every test, every advisory, the mileage at each one.
Due a test? Find an approved MOT station near you.