MOT fail rates by first-use year
2004 Porsche 911 MOT fail rate and common faults
How Porsche 911 cars first used in 2004 did at their MOTs from 2022 to 2025, against all cars of the same age. From 9,849 DVSA MOT tests of these cars. First use is usually the date the car was first registered.
MOT data updated
At 21 years, tested in 2025
What stands out
- In 2025, at 21 years old, Porsche 911 cars first used in 2004 failed 15.4% of MOTs (2,461 tests), 26.7 points below the 42.1% for all cars that age.
- From 2022 to 2025, as these cars went from 18 to 21 years old, the fail rate moved from 17.0% to 15.4%.
- Porsche 911 cars first used a year earlier, in 2003, failed 19.5% at the same age of 21 years (2,630 tests, in 2024).
- The most common fail item that is not a wear item, for the Porsche 911 at 21 years, is catalyst emissions: Lambda reading after 2nd fast idle outside specified limits, at 2.4 per 100 MOTs (all cars: 1.7).
MOT fail rate by test year
| Test year | Age | MOT fail rate | Tests (n) | All cars | Difference |
|---|---|---|---|---|---|
| 2022 | 18 years | 17.0% | 2,496 | 43.3% | −26.3 pts |
| 2023 | 19 years | 17.0% | 2,478 | 43.2% | −26.2 pts |
| 2024 | 20 years | 16.8% | 2,414 | 42.8% | −25.9 pts |
| 2025 | 21 years | 15.4% | 2,461 | 42.1% | −26.7 pts |
Most common faults at 21 years
These figures cover all Porsche 911 MOTs at 21 years: cars first used 2001 to 2004, tested 2022 to 2025 (n=9,171). The list uses every first-use year so it has enough tests. Wear items (tyres, brake pads, wipers, bulbs) say more about upkeep than about the design.
MOT fail items
| Fail item | Per 100 MOTs | All cars |
|---|---|---|
| Side/position light not working Wear | 2.6 | 4.9 |
| Catalyst emissions: Lambda reading after 2nd fast idle outside specified limits | 2.4 | 1.7 |
| Driveshaft CV boot split | 1.8 | 3.0 |
| Rigid brake pipes: excessively corroded | 1.4 | 2.5 |
| Wipers not clearing screen Wear | 1.2 | 3.5 |
| Dipped headlight not working Wear | 1.2 | 1.8 |
| Headlight aimed too high Wear | 1.0 | 1.2 |
| Headlamp aim: projected beam image is obviously incorrect Wear | 0.9 | 3.7 |
| Tyre tread below 1.6 mm Wear | 0.9 | 2.4 |
| Rear fog lamp: not working Wear | 0.9 | 1.4 |
Per 100 of the MOTs above (n=9,171). A test with two items counts once for each.
Advisories
| Advisory | Per 100 MOTs | All cars |
|---|---|---|
| Rigid brake pipes: corroded, covered in grease or other material | 12.2 | 15.9 |
| Brake discs: worn, pitted or scored, but not seriously weakened | 8.7 | 10.4 |
| Tyre tread close to the legal limit or worn on the edge Wear | 8.1 | 14.8 |
| Engine oil leaks: leak, but not excessive | 5.2 | 14.8 |
| Tyre condition: slightly damaged/cracking or perishing Wear | 4.5 | 10.4 |
| Exhaust system: has a minor leak of exhaust gases | 2.6 | 5.5 |
| Registration plate lamp(s): inoperative in the case of multiple lamps or light sources Wear | 2.3 | 5.3 |
| Windscreen: damaged but not adversely affecting driver's view | 2.1 | 3.9 |
| Suspension pin or bush worn, without excessive movement | 1.9 | 7.2 |
| Drive shaft joints: constant velocity boot severely deteriorated | 1.6 | 3.8 |
Per 100 of the MOTs above (n=9,171). A test with two items counts once for each.
Fuel type at 21 years
These figures cover all Porsche 911 MOTs at 21 years: cars first used 2001 to 2004, tested 2022 to 2025 (n=9,171). Each fuel is set against all cars of the same fuel and age. Fuels with fewer than 1,000 tests are not shown.
| Fuel | Share of tests | MOT fail rate | Tests (n) | All cars, same fuel | Median mileage |
|---|---|---|---|---|---|
| Petrol | 100.0% | 18.2% | 9,165 | 41.7% | 78,419 miles |
Fail rate by mileage at 21 years
These figures cover all Porsche 911 MOTs at 21 years: cars first used 2001 to 2004, tested 2022 to 2025 (n=9,171). At 21 years, Porsche 911 cars at 90,000 to 120,000 miles failed more often (21.7%, n=2,343) than those at 30,000 to 60,000 miles (12.3%, n=1,954). Bands with fewer than 1,000 tests are not shown.
| Mileage at test | MOT fail rate | Tests (n) | All cars |
|---|---|---|---|
| 30,000 to 60,000 miles | 12.3% | 1,954 | 33.5% |
| 60,000 to 90,000 miles | 18.5% | 3,560 | 40.6% |
| 90,000 to 120,000 miles | 21.7% | 2,343 | 44.7% |
Car tax rules for a 2004 car
- Cars first registered from 1 March 2001 to 31 March 2017 are taxed by CO2 emissions band, from band A (the lowest emissions) to band M. The band is set by the CO2 figure on the V5C logbook.
These are the rules, not the amount for a specific car. Car tax check
ULEZ and clean air zones
- Many petrol cars first registered from 2001 to 2005 already meet Euro 4, but not all of them. For a 2004 petrol car the Euro standard of that car decides.
- The clean air zones in Birmingham and Bristol use the same Euro 4 petrol and Euro 6 diesel standards. The low emission zones in Scotland use them too, but enforce them with fines, not a daily charge.
The Euro standard of the car decides, not the year alone. ULEZ checker
Other years of the Porsche 911
Other Porsche models first used in 2004
| Model | Age at test | MOT fail rate | Tests (n) | All cars |
|---|---|---|---|---|
| Porsche Boxster (2004) | 21 years in 2025 | 24.0% | 2,012 | 42.1% |
| Porsche Cayenne (2004) | 20 years in 2024 | 29.7% | 1,112 | 42.8% |
More on the Porsche 911
Found one you might buy? Vet the specific car.
These figures describe 2004 Porsche 911 cars as a group, not any one car. The VetTheCar Buying Report looks at the car you are buying: its MOT history, what similar cars did next, and what to ask the seller.
Source
Contains public sector information licensed under the Open Government Licence v3.0. Source: DVSA anonymised MOT test data, class 4 normal MOT tests, 2022 to 2025. MOT data updated 28 September 2026.
Not affiliated with or endorsed by DVSA. How we calculate these figures · Data sources
Car tax and clean air zone rules are summarised from GOV.UK and Transport for London guidance. They are general rules and are not drawn from the MOT data.