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MOT defects · Engine, exhaust and leaks

Engine warning light on MOT failure: what it means and which cars get it

In DVSA MOT data for 2023, analysed by RegTail, testers recorded this as a failure on at least 0.8 in 100 initial MOT tests. The Volkswagen Beetle got it most often: recorded 4.1 times per 100 of its 48,614 tests.

DVSA wording: Engine MIL illuminated indicating a malfunction.

Failures
0.8 in 100
At least 266,912 tests in 2023
Most often
Volkswagen Beetle
4.1 per 100 tests

What it means

The engine management warning light is on, meaning the engine's computer has logged a fault. It can be anything from a sensor to a misfire or an emissions fault, so the light alone does not say how serious it is.

How serious it is

A major defect, so a fail.

Source: MOT inspection manual for cars and light vans, section 8.2.1.2 and 8.2.2.2.

  1. 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.

What fixing it usually involves

A diagnostic scan reads the fault code, which points to the repair. Clearing the code without a repair only hides it until the light returns.

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

ModelTestsFail
Volkswagen Beetle48,614
4.1
Vauxhall Zafira229,031
3.8
Nissan Navara74,020
3.3
Mercedes-Benz Sprinter211,162
2.9
Vauxhall Vivaro229,686
2.7
Renault Trafic125,608
2.7
Vauxhall Meriva101,694
2.7
Mercedes-Benz CLK32,623
2.5
Vauxhall Movano51,019
2.5
Vauxhall Corsa948,473
2.5

What to check at a viewing

  1. On the car
    With the ignition on, the engine light should come on, then go out once the engine runs. A bulb that never lights at all may have been removed.
  2. In the MOT history
    If this appears in past results, ask what was done and when, and for the receipt.

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 "Engine warning light on" mean on an MOT?
The engine management warning light is on, meaning the engine's computer has logged a fault. It can be anything from a sensor to a misfire or an emissions fault, so the light alone does not say how serious it is.
Engine warning light on: is it an MOT fail?
A major defect, so a fail.
Which cars are most likely to get "engine warning light on" on an MOT?
In DVSA MOT data for 2023, analysed by RegTail, the models that got it most often were the Volkswagen Beetle (4.1 per 100 tests), the Vauxhall Zafira (3.8 per 100 tests), the Nissan Navara (3.3 per 100 tests).

More engine, exhaust and leaks defects

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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.