Airbag (SRS) Light On: MOT Pass or Fail?
Quick Answer
Yes. An illuminated airbag (SRS) warning lamp is an automatic major fail on any vehicle first used on or after 1 January 2003. The rule was added to the MOT in 2012. Common causes are a worn clock spring, a seat occupancy sensor fault or low battery memory after a flat. Fixes typically run £30-300.
The supplementary restraint system warning lamp is checked at every MOT and a glowing airbag light means an instant fail. Since 2012 the DVSA has treated SRS faults the same as ABS or engine management lamps: binary, with no advisory option. If yours has come on, run the reg through our free MOT history check and act before booking the test.
Will it fail your MOT? The exact rule
Section 7.1.5 of the DVSA MOT Inspection Manual lists the SRS malfunction indicator as a major defect when illuminated, indicating a fault, on any vehicle first used on or after 1 January 2003. Pre-2003 cars and motorbikes are not assessed.
The check applies to the airbag system as a whole, including front, side and curtain bags as well as seatbelt pretensioners. Any of those subsystems flagging a fault triggers the same warning lamp and therefore the same MOT result.
- SRS lamp on after engine start: major fail
- Bulb check that extinguishes: pass
- Lamp removed or taped over: major fail (tampering)
- Pre-2003 vehicle: not assessed
Why the airbag light comes on
The SRS module logs codes from dozens of sensors and squibs. Most UK MOT failures trace to a small group of repeat offenders, with the steering wheel clock spring leading the list on cars over six years old.
The clock spring is a flat ribbon cable that maintains electrical contact between the airbag and the steering column as the wheel rotates. Repeated steering inputs eventually break a strand, opening the airbag circuit and lighting the lamp. Seat occupancy mats in the passenger seat are the second most common culprit.
- Clock spring (steering wheel rotary coupler): £80-200 fitted
- Passenger seat occupancy sensor: £100-300
- Seatbelt pretensioner buckle switch: £50-150
- Low battery voltage during start: free reset
- Crash data stored after minor knock: scan-tool reset
How to spot it before the test
Watch the dashboard from key-on to engine-running. The airbag icon (a person with a circle in front) should illuminate during the bulb check and go out within around six seconds. If it stays lit, flashes a code or fails to come on at all, the system has a fault.
Many basic OBD-II scanners cannot read SRS codes — you need an enhanced tool such as iCarsoft, Foxwell NT630 Plus or a specialist scan at a garage. A typical airbag-specific diagnostic costs £30-50.
Cost to fix before MOT day
Sometimes the cheapest fix is the simplest. If the lamp came on after a flat battery or jump start, a sensible drive cycle plus a code clear with a scan tool will often restore normal operation at no part cost.
For mechanical faults, a clock spring replacement is usually the most expensive common job because it requires steering wheel removal and careful airbag handling. Seat occupancy mats are sometimes repaired with an aftermarket bypass resistor (around £15) but DVSA-approved testers will spot tampering.
- Battery memory reset: free with scan tool
- Seatbelt buckle switch: £50-150 fitted
- Clock spring: £150-300 fitted
- Passenger occupancy mat: £150-400 fitted
- Crash-stored data clear: £40-80 specialist
MOT history clues for buyers
An airbag fault that recurs across multiple MOT records is a serious red flag — it can indicate undisclosed accident damage. Run any used car through our free MOT history check and search the advisory text for 'airbag', 'SRS' or 'restraint'.
Pair the result with our common MOT faults database. Some models, like the Ford Fiesta Mk7 and BMW 1 Series E87, have known clock spring weaknesses that explain a single fail without implying crash damage.
Pre-test checklist
After the repair, clear the codes with a scan tool and verify the lamp extinguishes correctly on a key cycle. Some systems require an ignition-off period of 10 minutes before the module fully re-checks itself.
Never disable the airbag warning lamp by removing the bulb or taping over the cluster. Section 7.1.5 specifically lists tampering as a major defect, and you would also be facing a Construction & Use offence if stopped on the road.
Frequently Asked Questions
Can a flat battery cause the airbag light to stay on?
Yes. A deep-discharge or jump start can corrupt the SRS module's stored data, lighting the lamp until the codes are cleared with a scan tool. This is the cheapest cause to fix and a common DIY mistake to rule out first.
Is the airbag light treated the same as the ABS or engine warning light?
Yes. All three are binary major defects under the post-2018 MOT rules. None can be passed off as advisories, and tampering with the lamp is itself a fail.
Will the test still pass if the airbags are deployed but the lamp is off?
If the lamp is off the system reports no fault. However, deployed airbags must be replaced and a tester noticing physical evidence (covers loose, dash damage) may refuse the test. Insurance write-off status should also be checked.
How do I reset the airbag light after fixing the fault?
Most cars need a scan tool that supports SRS codes. Cheap generic OBD readers won't clear airbag faults. Independent garages typically charge £20-40 to clear codes after the underlying repair.
Does the rule apply to older cars without airbags?
No. Vehicles first used before 1 January 2003 are not assessed under Section 7.1.5. If your car has no SRS warning lamp from the factory, the test does not look at it.
Diagnose the SRS code, fix the underlying fault and clear the lamp with a scan tool before MOT day. Use our free MOT history check to confirm a used car hasn't been hiding repeated airbag failures.