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MOT defects · Corrosion and body

Excessive corrosion in the vehicle structure 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 0.2 in 100 and as a failure on at least 0.01 in 100 initial MOT tests. The Suzuki Jimny got it most often: recorded 4.1 times per 100 of its 25,207 tests.

DVSA wording: Vehicle structure corroded to the extent that the rigidity of the assembly is seriously reduced.

Failures
0.01 in 100
At least 2,948 tests in 2023
Advisories
0.2 in 100
At least 52,585 tests in 2023
Most often
Suzuki Jimny
4.1 per 100 tests

What it means

Rust has eaten into the load-bearing structure, the chassis on a separate-chassis vehicle or the body shell on most cars, so it is less stiff and strong. Testers judge it by eye, finger and thumb pressure and a light tap with a corrosion tool, not by surface rust alone. As an advisory the tester has seen corrosion that is not yet bad enough to fail.

How serious it is

A major defect, so a fail, when it significantly reduces the strength of the structure. If steering or braking is likely to be affected it is dangerous.

Source: MOT inspection manual for cars and light vans, section 6.1.1.

  1. Dangerous Fail
    A 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.
  2. Major Fail
    It may affect the vehicle's safety, put other road users at risk or have an impact on the environment. Repair it immediately.
  3. Advisory Pass
    It could become more serious in the future. Monitor and repair it if necessary.

What fixing it usually involves

Cutting out the rotten metal and welding in new steel. The cost depends on how far it has spread, and it can exceed the value of an older car.

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 17 models with at least 20,000 tests where it is among the 40 most common items. DVSA MOT data for 2023, analysed by RegTail.

ModelTestsFailAdvisory
Suzuki Jimny25,207
1.3
2.8
Mitsubishi Shogun35,550·
3.5
Mitsubishi L20078,544·
3.5
Land Rover Defender112,814·
3.4
Iveco Daily38,031·
2.8
Citroen Xsara35,042
2.5
·
Nissan Navara74,020·
2.5
Suzuki Grand Vitara24,508·
2.3
Ford Transit951,359·
1.6
Mazda MX-595,311·
1.4

What to check at a viewing

  1. On the car
    Look underneath at the sills, floor, jacking points and around the suspension mountings with a torch. Press firmly on suspect areas: metal should feel solid, not crusty or soft.
  2. In the MOT history
    If 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.

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Questions

What does "Excessive corrosion in the vehicle structure" mean on an MOT?
Rust has eaten into the load-bearing structure, the chassis on a separate-chassis vehicle or the body shell on most cars, so it is less stiff and strong. Testers judge it by eye, finger and thumb pressure and a light tap with a corrosion tool, not by surface rust alone. As an advisory the tester has seen corrosion that is not yet bad enough to fail.
Excessive corrosion in the vehicle structure: is it an MOT fail?
A major defect, so a fail, when it significantly reduces the strength of the structure. If steering or braking is likely to be affected it is dangerous.
Which cars are most likely to get "excessive corrosion in the vehicle structure" on an MOT?
In DVSA MOT data for 2023, analysed by RegTail, the models that got it most often were the Suzuki Jimny (4.1 per 100 tests), the Mitsubishi Shogun (3.5 per 100 tests), the Mitsubishi L200 (3.5 per 100 tests).

More corrosion and body defects

See every MOT defect we explain or MOT pass rates by model.

Excessive corrosion in the vehicle structureCorrosion near a suspension mountingNumber plate illegible or deteriorated

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.