ABS Warning Light - Will My Car or Motorcycle Fail a Roadworthy?
I inspected this BMW R1200GS Adventure in Darra today. Great bike, well looked after – but it failed. The ABS warning light stayed on during the test ride. That’s a fail, every time.
Safety-related warning lights that stay on are a fail
When you start the engine, all the warning lights on the dashboard come on briefly as a self-check. That’s normal. But once the engine is running and the vehicle is being driven, safety-related warning lights should all switch off.
If a safety-related warning light stays on, the vehicle cannot pass a roadworthy inspection. This includes the ABS light, the engine light, the airbag light, the stability control light, and other safety indicators.
Not every dashboard light is a roadworthy fail. A service reminder light – the one telling you the car is due for a scheduled service at the dealer – is not a safety warning and won’t fail an inspection.
The colour of the light doesn’t matter either. On this BMW, the ABS light was red, not orange. Whether a warning light is orange, red, or any other colour, if it indicates a safety system fault, it’s a fail.
ABS on motorcycles - it needs to roll first
On motorcycles with ABS, the warning light typically stays on after starting the engine. This is normal. The ABS system on most motorcycles needs the bike to roll a few metres before it completes its self-check and switches the light off.
So if you start your bike and see the ABS light on the dash, don’t panic. Ride it a short distance – even just down the driveway and back. If the light switches off after a few metres of movement, the system is working and it will pass.
If the light stays on after riding, there’s a fault in the ABS system. That’s what happened on this BMW in Darra – the light would not switch off no matter how far I rode it. The ABS system has a fault that needs diagnosing and repairing before the bike can pass.
ABS on cars - similar situation
On most cars, the ABS light switches off within seconds of starting the engine. But there are situations where the light may stay on temporarily:
If the battery has been disconnected recently or the car has been sitting for a long time, some ABS systems need the car to be driven a short distance before the light clears. Sometimes this means driving a few hundred metres, sometimes it means reaching over 50km/h before the system recalibrates and the light turns off.
If you’ve recently had battery work done or the car has been parked for weeks, take it for a short drive before your roadworthy inspection. If the ABS light clears during the drive, you’re fine. If it stays on, the system has a fault.
What does ABS actually do?
ABS stands for Anti-lock Braking System. It prevents the wheels from locking up under heavy braking. When you brake hard without ABS, the wheels can stop spinning entirely – the tyres lose grip and the vehicle skids. ABS detects when a wheel is about to lock and rapidly pulses the brakes on and off to maintain grip.
On a car, this means you can steer while braking hard in an emergency – the car stays controllable instead of sliding in a straight line.
On a motorcycle, ABS is even more critical. A locked front wheel on a motorcycle almost always results in a crash. ABS prevents that.
When the ABS warning light is on, it means the system is disabled. The normal brakes still work, but the anti-lock function is not operating. In an emergency braking situation, the wheels can lock and the vehicle can skid. That’s why it fails a roadworthy – the safety system is not functioning.
Common causes of ABS faults
Faulty wheel speed sensor – this is the most common cause. Each wheel has a sensor that tells the ABS system how fast it’s spinning. If a sensor fails or its wiring is damaged, the system can’t function and the light comes on.
Corroded or dirty sensor ring – the sensor reads a toothed ring on the wheel hub. If the ring is corroded or packed with dirt, the sensor can’t read it properly.
Low brake fluid – some ABS systems trigger the warning light when brake fluid drops below a certain level.
Faulty ABS module – the electronic control unit itself can fail, though this is less common and more expensive to fix.
A mechanic with a diagnostic scanner can read the fault code and tell you exactly what’s causing the light. Get it diagnosed before booking your roadworthy.
Check before you book
Start your car or motorcycle and watch the dashboard. Drive it a short distance. If any orange warning light stays on after driving, get it investigated before booking your roadworthy. It’s a guaranteed fail and you’ll save yourself a wasted inspection.
