Warning lights
Airbag warning light on: what it means and what to do
An airbag warning light means the restraint system's control unit has detected a fault and may have disabled one or more airbags or seat-belt pretensioners. The car drives the same, but in a crash the protection might not work.
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Reviewed by Daniel Morales, founder of Reprorace SL, on
Is it serious? Can I keep driving?
Carefully, and only as far as the garage. You can drive to the garage, but do so as soon as possible: the airbags' protection is not guaranteed. Do not tamper with connectors or parts of the system: airbags contain explosive charges and only a professional should handle them.
A careful, general answer: only someone who inspects the car can say whether it is safe to drive. When in doubt, stop somewhere safe and call for assistance.
Most likely causes
- Connectors under the seats: moving the seats or putting things underneath can loosen the side airbag or pretensioner connector.
- Steering wheel clock spring: the cable that connects the steering wheel airbag wears with turning.
- Low battery voltage: after a flat battery or a battery change, some cars store the fault.
- Crash or occupancy sensors: a faulty or disconnected sensor after a repair.
- Airbag control unit: after a crash in which airbags deployed, it may need replacing or reprogramming.
Listed from more to less common in general; on your car they may be different. A fault-code reading and a check at the garage confirm which one it is.
To understand it better: What does a pending, stored or permanent code mean? Can an OBD reader damage the car or drain the battery?
Car system: Airbags and passive safety
What you can check yourself
Think back to whether it came on after moving a seat, changing the battery or a repair: it is a useful clue.
Check that nothing is blocking or pulling on the cables under the seats, without unplugging anything.
Do not disconnect the battery or airbag connectors to reset the light.
Safe checks only: with the engine off and cold whenever you look under the hood, without taking anything apart and without touching hot or moving parts.
Related fault codes
- B0001Driver frontal stage 1 deployment control: malfunction
- B0020Left side airbag deployment control: malfunction
- U0151Lost communication with restraints control module
Generic codes that often come with this symptom. Seeing one does not confirm the cause: it is where the diagnosis starts.
How the ECO-LITE helps diagnose it
Plugged into the OBD socket, the ECO-LITE reads the fault codes of the control units that answer, with the freeze-frame data captured when the fault happened, and shows live data on your phone or computer. With your permission, your garage can see them remotely before you bring the car in.
What to look at here: the airbag control unit's codes (B and U) with their status, current or stored; system voltage.
Frequently asked questions
Do the airbags work with the light on?
There is no way to know: depending on the fault, the control unit disables the whole system or only part of it. Treat it as if they do not work.
Will the car pass the MOT with the airbag light on?
Usually not: the restraint system warning light is checked at the periodic inspection, and a light that stays on is a defect.
Can I clear it myself with a reader?
You can read it, but clearing it without a repair only hides the warning, and many airbag units will not clear a fault that is still present. Have a garage look at it.
Keep reading
- Airbags and passive safety: how they work and what fails
- ABS or ESP warning light on: what it means and what to do
- Car battery keeps going flat: causes and what to do
- Engine warning light on and steady: what it means and what to do
- Car symptoms: what they mean and what to do
- Check engine light on: what to do
- How to read and clear your car's fault codes
- OBD fault codes: what each one means