What actually fails an MOT
Not categories, but the specific items a tester writes down. Each one below is among the commonest faults on at least twenty different model-and-year combinations, so these are the faults worth knowing how to spot on any car you go and look at.
| Fault | Share of all tests | Models |
|---|---|---|
| Tyres tread depth below requirements of 1.6mm | 2.1% | 866 |
| Coil spring fractured or broken | 2.1% | 350 |
| Brake linings and pads less than 1.5 mm thick | 1.6% | 700 |
| Registration plate lamp(s) inoperative in the case of multiple lamps or light sources | 1% | 304 |
| Tyres has a cut in excess of the requirements deep enough to reach the ply or cords | 0.8% | 630 |
| Tyres has ply or cords exposed | 0.8% | 535 |
| Visibility does not clear the windscreen effectively | 0.8% | 485 |
| Position lamp not working | 0.8% | 222 |
| Suspension arms ball joint excessively worn | 0.8% | 154 |
| Suspension arms pin or bush excessively worn | 0.6% | 169 |
| Drive shafts constant velocity boot split or insecure, no longer prevents the ingress of dirt | 0.6% | 136 |
| Steering linkage components ball joint has excessive play | 0.6% | 100 |
| Lamps, reflectors and electrical equipment not working | 0.5% | 130 |
| Suspension has a serious fluid leak | 0.4% | 132 |
| Parking brake efficiency (sp) efficiency below requirements | 0.3% | 123 |
| Condition of glass damaged but not adversely affecting driver's view | 0.2% | 155 |
| Headlamps not working on dipped beam | 0.2% | 121 |
| Rigid brake pipes excessively corroded | 0.2% | 81 |
| Registration plate lamp(s) inoperative in the case of a single lamp or all lamps | 0.2% | 76 |
| Linkage ball joint dust cover ball joint dust cover no longer prevents the ingress of dirt | 0.2% | 62 |
| Tyres has a bulge, caused by separation or partial failure of its structure | 0.1% | 178 |
| Compression ignition inoperative or indicates a malfunction | 0.1% | 128 |
| Visibility provides insufficient washer liquid | 0.1% | 78 |
| Rbt excessively binding | 0.1% | 54 |
| Linkage ball joints ball joint excessively worn | 0.1% | 48 |
| Tyres malfunctioning or obviously inoperative | 0.1% | 46 |
| Spark ignition inoperative or indicates a malfunction | 0.1% | 42 |
| Visibility not working | 0.1% | 40 |
| Headlamp aim projected beam image is obviously incorrect | 0.1% | 33 |
| Body, chassis, structure has a major leak of exhaust gases | 0.1% | 27 |
| Suspension has an excessively worn bush | 0.1% | 26 |
| Suspension arms ball joint dust cover no longer prevents the ingress of dirt | 0.1% | 23 |
| Brake discs and drums significantly and obviously worn | 0% | 53 |
| SRS malfunction indicator lamp warning lamp indicates a fault | 0% | 35 |
| Flashing type not working | 0% | 31 |
| Rbt inoperative on one side | 0% | 27 |
| Tyres has a tear, caused by separation or partial failure of its structure | 0% | 26 |
| Visibility blade defective | 0% | 26 |
| Catalyst emissions Lambda reading after 2nd fast idle outside specified limits | 0% | 24 |
| Rear fog lamp not working | 0% | 22 |
| Headlamp aim too low | 0% | 20 |
Data: DVSA anonymised MOT tests and results, 2023. Class 4 standard tests only. Contains public sector information licensed under the Open Government Licence v3.0.