Airbag (SRS) warning light: what it means and what to do

The airbag light usually shows a seated person with a large circle in front of them, or the letters "SRS" (supplemental restraint system). On many cars it is red. Symbols differ between makes, so check your owner's manual.

It should come on for a few seconds when you switch on the ignition while the system tests itself, then go out. If it stays on, flashes, or comes on while you drive, the system has found a fault. The RAC says that when it is on, the airbags may not go off in a crash, or could even go off unexpectedly.

Is it an emergency? The car brakes, steers and drives as normal. What you lose is crash protection, for you and your passengers. That is why this is a "fix it soon" light rather than a "stop now" one, but do not leave it. The RAC advises not driving at all with the red airbag light on; the AA says to get the car checked at a garage as soon as possible. Some cars also use a separate light to show the passenger airbag is switched off; that one is a reminder, not a fault.

Never work on airbag parts yourself. Airbags fire with explosive force. Unplugging, probing or removing airbag modules, the steering wheel, seats with side airbags or seatbelt tensioners can set one off and injure you. This is a garage job.

Likely causes, most common first

1. Passenger airbag switched off

   Some cars have a key switch or button to turn off the passenger airbag for a rear-facing child seat. If it has been switched off, a light stays on as a reminder. Check your owner's manual for where the switch is, and switch it back on if there is no child seat.

2. Seatbelt buckle or seat sensor fault

   The system checks whether belts are fastened and whether someone is in the passenger seat. A faulty buckle switch, seat sensor, or its wiring under the seat can turn the light on. A heavy bag on a seat with no belt fastened can also confuse it.

3. Worn clock spring in the steering wheel

   The clock spring is a coiled ribbon cable that keeps the driver's airbag connected while the wheel turns. When it wears, the horn or steering wheel buttons often stop working too.

4. Low battery voltage or a recent flat battery

   A weak battery or a jump-start can make the airbag computer store a fault. The code may need clearing even after the battery is fine again.

5. Crash sensor, wiring or control unit fault

   Impact sensors, connectors and the airbag control unit can fail, for example from corrosion or water damage. After a collision, deployed airbags or fired seatbelt tensioners must be replaced and the system reset.

What it costs to fix

The first step is always a diagnostic check: a garage connects a scanner that reads the airbag control unit's fault codes, which point to the faulty part. A loose connector or a seat sensor is usually a far cheaper fix than replacing an airbag or the control unit. Prices vary a lot by car and by part, so ask for a quote once the code has been read.

DIY or garage?

How to prevent it

• Keep the battery healthy; a weak battery can set airbag faults.
• Do not push heavy items under the front seats, where wiring and sensors sit.
• Have airbags and tensioners replaced only by a qualified garage after a crash.
• Check for open safety recalls on your car with the manufacturer or your national recall service.