Does the engine warning light fail an MOT?

Yes. An illuminated engine management light (EML) is a major defect and causes an automatic MOT failure. The car must be diagnosed and the fault resolved before the test.

Does the ABS light fail an MOT?

Yes. An ABS warning light that remains on during the test is a major defect and will cause an MOT failure. ABS is considered a primary safety system.

Does the airbag warning light fail an MOT?

Yes. An SRS/airbag warning light that stays on is a major defect under MOT rules introduced in 2018. This causes an automatic failure.

Does the tyre pressure light (TPMS) fail an MOT?

Yes, if the TPMS light remains illuminated throughout the test it is recorded as a major defect and causes a failure. Correct the tyre pressure and the light should extinguish.

Does the DPF warning light fail an MOT?

A DPF warning light itself is not listed as a direct failure reason, but the underlying issue — a blocked DPF — will typically cause the emissions test to fail.

Dashboard Warning Lights That Cause MOT Failure — High Wycombe Guide 2026

An illuminated warning light on your dashboard is not just a nuisance — several of them will cause an automatic MOT failure in High Wycombe. Here's exactly which lights fail, which are advisories, and what to do about each one before test day.

Dashboard Warning Light MOT Guide

Click any warning light to see its MOT impact and what to do

Engine Management Light (EML)

⚠ Automatic MOT Failure

An illuminated engine management light is a major defect under DVSA rules and causes an automatic MOT failure. The light indicates a fault detected by the engine control unit — this could be anything from an oxygen sensor to a misfiring cylinder or emissions system fault. The specific fault code must be diagnosed with a scan tool before the issue can be resolved. Auto Clinics offers full diagnostic scanning at our High Wycombe garage — we'll read the fault code and quote for the fix before any work is carried out.

Before your MOT: Have the fault code read and the underlying issue resolved. Don't attempt to clear the code without fixing the fault — testers check for incomplete readiness monitors.

The Rule: DVSA Major vs Minor vs Dangerous

Since May 2018 the MOT has used three defect categories. Dangerous defects mean the vehicle cannot be driven away; Major defects (which include most warning lights) cause an automatic fail; Minor defects are noted but do not fail the test. Warning lights that stay on during the test are classified as major defects under the "driver's view of road" and "driver controls" categories.

Can I Clear a Warning Light Before the MOT?

Clearing a fault code with a diagnostic tool without fixing the underlying fault is not a solution. DVSA testers are required to check whether the vehicle's on-board diagnostic system shows any incomplete readiness monitors — a sign that codes have been recently cleared. If monitors are incomplete, the tester is permitted to fail the test on that basis. The only legitimate way to pass with a clear dashboard is to resolve the fault.

2018

Year DVSA added warning lights as major defects

Major

Classification for EML, ABS, airbag and TPMS lights

Defect categories: Dangerous, Major, Minor

Same day

Diagnostic scans available at Auto Clinics HW

Warning Light On? Get It Diagnosed in High Wycombe

Full OBD diagnostic scan · Fault codes read & explained · Quote before any work · Same-day available

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Dashboard Warning Lights That Fail Your MOT — High Wycombe 2026

The Rule: DVSA Major vs Minor vs Dangerous

Can I Clear a Warning Light Before the MOT?

More MOT High Wycombe Guides