Why Is My ABS Warning Light On?
Charlotte Phillips, 18 days ago
5 min read
- Brakes
- Diagnostic
- Lights
FixMyCar discusses what can go wrong with a car's ABS system.
Bringing your car to a stop quickly can be tricky, especially when the road surface is slippery. Fortunately, the anti-lock braking system (ABS) offers a helping hand with this. But like any system, it isn't perfect and can sometimes go wrong. This guide discusses the most common reasons for ABS failure.
Contents
How does ABS work?
Sometimes, when a lot of pressure is applied to the brakes, the axle and wheels stop turning, causing the car to skid. The anti-lock braking system allows the driver to maintain control of the vehicle in situations like this.
Sensors detect if a wheel is about to lock up when the brakes are applied. Then, hydraulic valves, responsible for regulating the pressure in the braking system, release to reduce the braking pressure slightly to prevent a lock-up. As a result, the driver can maintain steering control, which locked wheels would usually prevent.
ABS was introduced as a safety feature on all new cars from the 1970s onwards, and by 2004, it was made compulsory by law for all new vehicles.
Learn more about how brakes work.
Common ABS problems
While ABS is generally reliable, it can fail for several reasons. When this happens, your car will notify you of a problem through the ABS warning light on the dashboard. There are four main problems that can trigger the ABS light:
Malfunctioning sensor
Faulty wiring
Malfunctioning controller
Faulty ABS light
A fifth reason the light might come on is to signal that the system is switched off. Check your owner's manual to find out how to switch it on - if the system is active but the light is still on, there's likely a problem. The only sure way to know the exact cause is for a trained mechanic to inspect the vehicle for you.
Malfunctioning ABS sensor
The ABS sensors are found on the brakes of your car. Over time, dirt and grime can build up on them from the road surface. When this happens, the sensors eventually malfunction, and error codes are sent to the main computer, triggering the ABS warning light.
You can sometimes solve this problem by cleaning the sensors. However, they may need to be replaced if the problem can’t be resolved.
Malfunctioning ABS light
When you start your car, the ABS light will briefly light up to make sure the system is working before switching back off. If the ABS light switches on at any other time, it could indicate a computer problem or a system malfunction. An electrical short can often be the culprit behind this problem, which would cause the ABS light to turn on and off.
Faulty wiring
The wiring that controls the ABS is vulnerable to wear and tear over time. When it becomes damaged, the dashboard warning light may be triggered, or the entire ABS could be disabled, which is dangerous if your vehicle skids.
Malfunctioning ABS controller
The ABS controller monitors the speed of your wheels and how fast the car is moving. It can engage the ABS to stop your vehicle from skidding. If the controller malfunctions, the anti-brake lock system will fail, and your ABS warning light will be illuminated.
How much does it cost for an ABS repair?
It costs around £89.35 for an ABS repair. You can find the average price of an ABS system diagnostic by manufacturer in the table below.
| Average cost of ABS diagnostic by manufacturer | |
|---|---|
| Audi | £61.90 |
| BMW | £87.51 |
| Citroen | £56.62 |
| Fiat | £79.89 |
| Ford | £73.49 |
| Mercedes | £272.31 |
| MINI | £212.44 |
| Nissan | £60.84 |
| Peugeot | £68.67 |
| Renault | £62.41 |
| Skoda | £53.51 |
| Toyota | £87.97 |
| Vauxhall | £89.73 |
| Volkswagen | £84.52 |
| Volvo | £87.33 |
Unsure why your ABS warning light is switched on? FixMyCar can help you find a trained mechanic in your area to diagnose the problem.
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