1,138 tests in 2025
Triumph Stag reliability and MOT pass rate
84.9% passed first time. The 15.1% fail rate is 7.5 points better than the all-car average, on a median example 51 years old with 56,381 miles.
Pass rate
84.9%
22.6% of all cars failed; 15.1% of these did.
Fixed on the day
3.1%
Passed after a defect was put right during the visit.
Median at test
56,381 mi
51 years old.
Fail rate by age
| Age at test | Tests | Fail rate |
|---|---|---|
| 3-5 years | 1 | — |
| 6-9 years | 0 | — |
| 10-13 years | 0 | — |
| 14+ years | 1,137 | 15.1% |
What the Stag 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 equipment7 dangerous45.9%
- Brakes22 dangerous39%
- Suspension1 dangerous25.6%
- Visibility23.8%
- Noise, emissions and leaks19.2%
- Steering1 dangerous16.3%
- Body, chassis, structure1 dangerous8.7%
- Seat belts and supplementary restraint systems4.7%
The exact defects that fail it
Every failure item DVSA recorded against a Stag in 2025, counted by how many tests each one appeared on.
- 1Service brake imbalance: across an axle26 tests
- 2Non catalyst emissions: emissions carbon monoxide content excessive23 tests
- 3Washers: not working17 tests
- 4Rbt (sp): efficiency below requirements15 tests
- 5Headlamp: not working on dipped beam14 tests
- 6Headlamp: not working on main beam14 tests
- 7Position lamp: not working14 tests
- 8Stop lamp: not working13 tests
What wears out first
Advisories are the tester flagging wear that is still legal. A typical Stag collects 2.61 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.
- 1Engine oil leaks: leaking excessively from engine151 tests
- 2Wheel bearings: has excessive play101 tests
- 3Transmission oil leaks: leaking excessively from transmission59 tests
- 4Pins and bushes: pin or bush excessively worn40 tests
- 5Non-component advisories: Play in steering rack inner joint(s)31 tests
- 6Steering column: top bearing excessively worn30 tests
- 7Other components: leaking26 tests
- 8Exhaust system: has a major leak of exhaust gases25 tests
Questions
What is the Triumph Stag MOT pass rate?
84.9% of the 1,138 Triumph Stag first-attempt MOTs in 2025 passed. The fail rate of 15.1% compares with 22.6% across all cars. A further 3.1% passed after a defect was fixed during the test visit.
What does a Triumph Stag usually fail on?
The single most common failure is "Service brake imbalance: across an axle", recorded on 26 failed tests, followed by "Non catalyst emissions: emissions carbon monoxide content excessive" and "Washers: not working". By section, lamps, reflectors and electrical equipment appears in 45.9% of failures, brakes appears in 39% of failures, suspension appears in 25.6% of failures.
Does age change the odds?
Sharply. At 3 to 5 years old the fail rate was 0%; at 14+ years it was 15.1%. The median Triumph Stag tested in 2025 was 51 years old with 56,381 miles.
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 Stag trim together. Year-on-year figures come from the same DVSA extracts for 2026 and earlier years. Full method on the pass rates hub.
Checking a particular Stag?
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.