ABS Light (What To Do When It Comes On)

28 Feb 2017 by Sam Bisby
ABS light

So, your ABS light has come on and you’re wondering what you should do next. That’s no surprise, given that your anti-lock braking system may have suffered a serious failure which, at its worst, could severely affect how your car performs under braking, especially in wet or icy conditions.

What does ABS do?

Your ABS, or anti-lock braking system, does exactly what it says; it prevents your car’s wheels from locking up under hard braking, thereby maintaining more control and limiting the chances of your car skidding.

When you brake hard, perhaps to avoid a collision, sensors on each of your car’s wheels send messages to the engine control unit, or ECU, letting it know which wheels may lock up and skid. Your ECU then intermittently releases the brakes on each wheel to prevent them from locking up and allowing you to maintain control of your vehicle.

When you start your car, the ABS light will come on automatically. This is because your car always checks the ABS system on starting; if there’s no problem the light will go off. If the light stays on, it’s a sign that there’s a problem with your car’s ABS system.

What could cause the ABS light to come on?

There are a variety of things that can cause the ABS light to come on and there are some things you can do to identify some of them.

Firstly, you should check your brake fluid reservoir to ensure that the levels aren’t too low, as the ABS warning light can be activated if the levels of brake fluid have dropped. If this is clearly an issue, you can top the brake fluid up yourself, which should cause the ABS light to go off.

If this doesn’t work, it’s a clear sign of a more serious problem that you may not be able to see yourself. It could be that one or more of the wheel sensors, that feed information back to the ECU, has become damaged in some way. This could cause it to report abnormal readings, or not report any at all, causing the ECU to report a fault with the ABS.

The ABS warning light could also have come on due to a loss of pressure in the braking system, which could be caused by cracks or splits in the brake fluid reservoir or brake lines. These are both issues that would likely be identified by tests carried out by trained technicians in a garage.

What to do when your ABS light comes on

If your ABS light comes on individually, you are safe to drive your car to your destination, as your normal brakes will still work. You will, of course, have to be more careful as your ABS will not respond in case of an emergency. You should book your car into your local garage as soon as possible so that they can run diagnostic tests to identify the cause(s) of the anti-lock brakes warning light.

However, if both the ABS light and brake warning light are illuminated together, it signifies a much more serious problem and you should not continue to drive. If this happens, you should bring your car to a steady stop, being very careful with your brakes, reducing your speed gradually. Once you’ve stopped in a safe place and switched your engine off, you should call your breakdown service or local garage and have your vehicle recovered.


If you have other warning lights illuminated on your dashboard and would like to know what they mean, make sure to read Dashboard Warning Lights Explained.

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