Sub-frame corroded MOT advisory: what it means and which cars get it
In DVSA MOT data for 2023, analysed by RegTail, testers recorded this as an advisory on at least 0.6 in 100 initial MOT tests. The Vauxhall Vectra got it most often: recorded 7.2 times per 100 of its 39,116 tests.
DVSA wording: A suspension component excessively damaged or corroded.
What it means
The sub-frame, the frame that carries the engine or suspension and bolts to the body, is rusting. As an advisory it means corrosion the tester could see but not bad enough to fail; it tends to get worse each winter.
How serious it is
A major defect, so a fail, when excessively damaged or corroded. Fractured or likely to fail is dangerous.
Source: MOT inspection manual for cars and light vans, section 5.3.3.
- Dangerous FailA direct and immediate risk to road safety or has a serious impact on the environment. Do not drive the vehicle until it's been repaired.
- Major FailIt may affect the vehicle's safety, put other road users at risk or have an impact on the environment. Repair it immediately.
- Advisory PassIt could become more serious in the future. Monitor and repair it if necessary.
What fixing it usually involves
Depending on how far it has gone, cleaning and treating the rust, welding in repairs, or replacing the sub-frame, which is a large job.
A general guide, not a quote: ask a garage to inspect the car.
Which models get it most
Per 100 initial MOT tests on each model, among the 67 models with at least 20,000 tests where it is among the 40 most common items. DVSA MOT data for 2023, analysed by RegTail.
| Model | Tests | Advisory |
|---|---|---|
| Vauxhall Vectra | 39,116 | 7.2 |
| Toyota Avensis | 72,103 | 4.9 |
| Jaguar XJ | 25,292 | 4.9 |
| Peugeot 107 | 119,430 | 4.4 |
| Jaguar XF | 102,260 | 4.2 |
| Honda Accord | 30,345 | 4.0 |
| Mazda 2 | 123,364 | 3.9 |
| Volvo XC90 | 62,177 | 3.5 |
| Kia Rio | 98,946 | 3.3 |
| Vauxhall Antara | 22,582 | 3.2 |
What to check at a viewing
- On the carLook underneath at the front and rear sub-frames with a torch for flaking, layered rust or holes, and ask whether it has been treated or repaired.
- In the MOT historyIf this appears as an advisory, see whether it came back at the next test or turned into a failure, and ask the seller for the receipt if it was fixed.
Check a specific car
Fleet averages only go so far. Enter the registration to see that car's own MOT history, mileage record and current condition, free.
Questions
What does "Sub-frame corroded" mean on an MOT?
Sub-frame corroded: is it an MOT fail?
Which cars are most likely to get "sub-frame corroded" on an MOT?
More suspension and steering defects
See every MOT defect we explain or MOT pass rates by model.
How these figures are made. We counted the defects recorded at every initial MOT test (not retests) of cars and light vans in Great Britain in 2023 in the DVSA anonymised MOT dataset, 33,842,940 tests in all. Each item counts once per test. A failure is a major or dangerous defect, including one fixed during the test. A model's rate is the share of its tests where the item was recorded.
For each model we keep its 40 most frequent items, so a model where a defect is rarer than that is not listed, and figures for all cars are a floor. Defect names and explanations are ours, checked against the MOT inspection manual; DVSA's own wording is shown under each name.
Contains public sector information licensed under the Open Government Licence v3.0. RegTail's analysis of the DVSA anonymised MOT dataset, 2023 tests.