Bob's Mechanical Repairs

Airbag warning lamp indicates a fault — MOT failure explained

Bob's Mechanical Repairs — independent family-run garage in Birnam, Dunkeld, Perthshire. Call 01350 727 276 or email [email protected].

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The SRS warning light stayed on with the engine running, meaning the airbag system has logged a fault and may not deploy correctly. It's a testable item on cars fitted with airbags.

Wording as it commonly appears on an MOT certificate: “Airbag warning lamp indicates a fault”.

What does it mean?

The SRS warning light stayed on with the engine running, meaning the airbag system has logged a fault and may not deploy correctly. It's a testable item on cars fitted with airbags.

How serious is it?

Usually recorded as: Major. The tester assesses the actual vehicle on the day, so your certificate is what counts.

What normally causes it?

  • A broken wire or corroded connector under a front seat — the usual suspect, because the loom flexes every time the seat is moved
  • A failed clock spring in the steering column, which also often kills the horn and wheel controls
  • A seat occupancy or belt pretensioner sensor fault
  • A previously deployed airbag never properly reset

What a mechanic would check

Read the SRS system with equipment that can actually talk to it — a basic code reader often can't. Then check the obvious mechanical suspects first: the connectors under the seats and the clock spring. Never start pulling airbag connectors about without disconnecting the battery and letting the system discharge.

What might need replacing

  • A connector or wiring repair under the seat
  • A clock spring
  • A sensor or, less often, an SRS module

Can you still drive it?

It's a failure. Mechanically the car may be fine, but with the light on you cannot assume the airbags will work in a crash — and that's the whole point of them.

More seat belts and restraints failures · MOT failure decoder · Ask a mechanic about your certificate

This is general guidance from a UK mechanic, not a substitute for a physical inspection. Only the tester who inspected your vehicle can confirm what was recorded and why.

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