Airbag Warning Light On — SRS Fault Explained

The airbag warning light (usually showing a person with a circle — representing the airbag — or labelled SRS) means there's a fault in the Supplemental Restraint System. This covers all airbags (front, side, curtain) and seatbelt pretensioners.

The critical safety implication:

With the airbag warning light on, your airbags may not deploy in an accident. This dramatically increases the risk of serious injury in a collision that your car would otherwise have protected you from. It's not merely an MOT issue — it's a genuine safety concern.

MOT: An illuminated airbag warning light is an automatic MOT failure.

Common causes:

Faulty clock spring — the most common cause. The clock spring is a coiled electrical connector inside the steering column that allows the steering wheel airbag to maintain its electrical connection while the wheel turns. It wears out, particularly on cars where the steering wheel is frequently adjusted. Symptoms often include the light appearing after the steering wheel position has been changed. Replacement costs £60–150 for parts, 1–2 hours labour.

Seat belt pretensioner fault — the pretensioner is a small explosive charge that tightens the seatbelt in a crash. If it detects a fault, the whole SRS system flags a warning. Often caused by a faulty connector under the seat, particularly on cars where seat rails have moved and stretched or damaged wiring.

Faulty airbag sensor — impact sensors in the front and sides of the car detect collisions. Corrosion or damage causes false fault readings.

Fault after a minor collision — even a low-speed bump can trigger an airbag sensor without the bags deploying. The system needs resetting by a garage with appropriate diagnostic equipment.

Flat backup battery — the SRS system has its own backup battery to deploy airbags even if the main battery is disconnected in a crash. When this small backup battery fails, the SRS light illuminates.

Water damage — airbag modules and connectors under seats are vulnerable to water ingress from flooding or spills.

Warning: Never attempt to work on airbag components yourself. The system contains explosive charges and capacitors that retain dangerous charge even after the battery is disconnected.