Only where it matters. Rust fails in a 'prescribed area', load-bearing structure within 30cm of where the brakes, steering, suspension or seat belts are mounted, if it has made a hole, the metal gives under finger and thumb pressure, or the tester's tool goes through. Elsewhere it fails only if it seriously weakens the structure or affects parts like brake pipes.
Testers grade each defect: a major or dangerous defect fails the MOT, a minor one passes but is written on the certificate.
| Defect | Result |
|---|---|
| Reservoir has minor damage or corrosion | PassesMinor |
| Reservoir heavily damaged, heavily corroded or leaking | FailsMajor |
| Defect | Result |
|---|---|
| Brake pipe damaged or excessively corroded | FailsMajor |
| Defect | Result |
|---|---|
| Brake hose ferrules excessively corroded | FailsMajor |
| Brake hose ferrules excessively corroded and likely to fail | FailsDangerous |
| Defect | Result |
|---|---|
| Component excessively worn or corroded | FailsMajor |
| Defect | Result |
|---|---|
| Actuator excessively corroded | FailsMajor |
| Actuator excessively corroded and likely to crack | FailsDangerous |
| Defect | Result |
|---|---|
| Other braking system (e.g. antifreeze pump, air dryer etc.) component damaged or corroded to the extent that the braking system is adversely affected | FailsMajor |
| Other braking system (e.g. antifreeze pump, air dryer etc.) component damaged or corroded leaking and system functionality adversely affected | FailsDangerous |
| Defect | Result |
|---|---|
| A suspension component excessively damaged or corroded | FailsMajor |
| Defect | Result |
|---|---|
| Vehicle structure corroded to the extent that the rigidity of the assembly is significantly reduced | FailsMajor |
| Vehicle structure corroded to the extent that steering or braking is likely to be adversely affected | FailsDangerous |
| Defect | Result |
|---|---|
| A towbar component damaged, defective, fractured or corroded | FailsMajor |
| Defect | Result |
|---|---|
| A body panel or body component damaged or corroded and likely to cause injury when grazed or contacted, or insecure | FailsMajor |
| Defect | Result |
|---|---|
| Body, cab or chassis excessively corroded at mounting points | FailsMajor |
| Body, cab or chassis corroded at mounting points to the extent that overall security or stability is seriously impaired | FailsDangerous |
From DVSA's MOT inspection manual for cars and passenger vehicles. Contains public sector information licensed under the Open Government Licence v3.0.
In 2025, 440,807 car MOTs failed on rust: 1.40%, or about 1 in 71. 3% of those failures were for a dangerous defect. Another 12 MOTs recorded it as a minor defect, which passes. Testers also noted it as an advisory on 2,934,355 MOTs: something to keep an eye on that didn't fail the test.
Share of the MOTs that failed on rust. One MOT can fail for more than one reason.
Share of car MOTs in each mileage band that failed on rust.
7.16% of MOTs on cars registered in 2005 failed on rust, against 0.00% for cars registered in 2022.
Models that failed on rust at least 1.15 times as often as the average car of the same age and mileage, out of 83 with at least 30 MOTs failed on it.
Least often: BMW X3 (0.0×), Volvo XC60 (0.1×), Audi A1 (0.1×), Peugeot 3008 (0.1×), Volvo XC90 (0.1×).
Only where it matters
In 2025, 440,807 car MOTs failed on rust, about 1 in 71. 3% of those were rated dangerous.
1 in 71car MOTs failed on rust in 2025
12minor defects recorded in 2025, which pass
Only where it matters. Rust fails in a 'prescribed area', load-bearing structure within 30cm of where the brakes, steering, suspension or seat belts are mounted, if it has made a hole, the metal gives under finger and thumb pressure, or the tester's tool goes through. Elsewhere it fails only if it seriously weakens the structure or affects parts like brake pipes.
In 2025, 440,807 car MOTs failed on rust: 1.40%, or about 1 in 71. 3% of those failures were for a dangerous defect.
Against the average car of the same age and mileage, the Ford Transit Custom (7.4 times as often), Dacia Duster (4.4 times as often) and Toyota Aygo (2.8 times as often), going by 2025 MOT results.