Why is My ABS Light On? What it Means and What to Do

Seeing the ABS light appear on your dashboard can be concerning, particularly if you're unsure whether your car is still safe to drive.

The ABS warning light is there to alert you to a potential problem with your vehicle's Anti-lock Braking System. While an illuminated ABS light does not necessarily mean your brakes have completely failed, it can mean an important safety feature is no longer working as it should.

So, what does the ABS light mean, why has it come on and can you drive with the ABS light on?

In this guide, Sandicliffe explains everything you need to know about the ABS warning light, including common causes, what to do when it appears, MOT implications and when your vehicle needs professional attention.

What Does the ABS Light Mean?

ABS stands for Anti-lock Braking System.

The ABS is designed to help prevent your wheels from locking when you brake heavily. By monitoring the speed of individual wheels and adjusting braking pressure when necessary, the system can help you maintain steering control during emergency braking.

The ABS warning light is normally displayed as the letters "ABS" inside a circle. The exact symbol can vary depending on your vehicle.

It is normal for the ABS light to briefly illuminate when you start your car while the vehicle performs its initial system checks.

However, if the ABS light stays on after starting the engine, or comes on while you're driving, your vehicle may have detected a fault.

Why Is My ABS Light On?

There are several possible reasons why your ABS light is on. Some are relatively straightforward, while others require specialist diagnosis.

1. Faulty ABS Wheel Speed Sensor

One of the most common causes of an ABS warning light is a problem with a wheel speed sensor.

These sensors monitor how quickly each wheel is rotating and send information to the ABS control module. If a sensor becomes damaged, dirty, corroded or develops an electrical fault, the system may receive inaccurate information.

This can trigger the ABS light.

2. Damaged ABS Reluctor Ring

The ABS sensor works alongside a reluctor ring to monitor wheel rotation.

If the reluctor ring becomes damaged, cracked or corroded, the sensor may not be able to accurately measure wheel speed.

A damaged reluctor ring can therefore cause an ABS fault and illuminate the warning light.

3. ABS Wiring or Electrical Fault

The ABS system relies on electrical connections and wiring throughout the vehicle.

A damaged cable, loose connection, corrosion, blown fuse or other electrical issue can interrupt communication between ABS components.

In some cases, electrical problems can also cause the ABS warning light to appear intermittently.

4. Faulty ABS Control Module

The ABS control module is responsible for processing information from the wheel speed sensors and controlling the ABS system.

If the module develops a fault, it may be unable to operate the system correctly.

Because ABS control modules are complex components, specialist diagnostic equipment is normally required to identify this type of problem.

5. Low Brake Fluid

Low brake fluid can also be associated with braking-system warning lights.

Brake fluid levels can fall as brake components wear, but a significantly low level can also indicate a leak or another problem.

If your brake fluid is low, the cause should be investigated rather than simply topping it up and ignoring the warning.

6. ABS Pump or Hydraulic Unit Fault

The ABS hydraulic unit helps control brake pressure when ABS activates.

A fault with the ABS pump or hydraulic unit can prevent the system from operating correctly and may cause the ABS light to come on.

This type of issue generally requires professional diagnosis and repair.

Can You Drive With the ABS Light On?

This is one of the most common questions drivers ask:

Can you drive with the ABS light on?

If the ABS light is illuminated but there are no other brake warning lights and your brakes feel completely normal, your conventional braking system will often continue to operate.

However, the ABS function may not be available.

This means your wheels could potentially lock under heavy braking, particularly in an emergency or on slippery roads.

If you need to drive the vehicle before it can be inspected:

• Drive cautiously.

• Leave additional stopping distance.

• Avoid harsh braking where possible.

• Take extra care in wet, icy or slippery conditions.

• Arrange an ABS diagnostic check as soon as possible.

What If the ABS Light and Brake Light Are Both On?

If your ABS light and brake warning light are on at the same time, you should take the situation more seriously.

The combination can indicate a problem affecting the vehicle's wider braking system.

If you notice changes in brake pedal feel, reduced braking performance, unusual noises or difficulty stopping, find somewhere safe to stop and seek professional assistance.

Do not continue driving if you believe your brakes are not working correctly.

What Should You Do When the ABS Light Comes On?

If your ABS warning light comes on, there are several things you can do.

Check for Other Warning Lights

Look at the dashboard to see whether any additional warning lights have appeared.

Pay particular attention to the brake warning light, traction control warning light and electronic stability control warning light.

Multiple warning lights may provide useful information about the underlying fault.

Check Your Brake Fluid

If you know how to do so safely, check your brake fluid level against the markings on the reservoir.

If the level is low, the vehicle should be inspected to establish why.

Restart Your Car

Turn the vehicle off and restart it.

A temporary electrical fault can sometimes cause a warning light to appear. If the ABS light disappears and stays off, the issue may have been temporary.

However, if the light returns, you should arrange a professional inspection.

Arrange an ABS Diagnostic Check

The most reliable way to establish why your ABS light is on is to have the vehicle professionally diagnosed.

Specialist diagnostic equipment can read fault codes stored within the ABS system and help technicians identify the affected component.

How Is an ABS Fault Diagnosed?

An ABS diagnostic check can provide valuable information about why the warning light has appeared.

A technician may check:

• ABS fault codes

• Individual wheel speed sensors

• Sensor wiring and connectors

• ABS reluctor rings

• Brake fluid levels

• ABS control module

• ABS pump and hydraulic unit

• Related electrical components

A diagnostic scan does not necessarily mean a component needs replacing. It helps identify where the problem is so the appropriate repair can be carried out.

How Much Does It Cost to Fix an ABS Light?

There is no single ABS repair cost because the price depends on the cause of the fault.

For example, replacing an ABS wheel speed sensor may be relatively straightforward, while repairing wiring or replacing an ABS control module can be more involved.

This is why diagnosing the fault first is important.

An illuminated ABS light does not automatically mean you need a new ABS sensor.

A professional diagnostic check can establish which component is responsible before repair work begins.

Will an ABS Light Fail an MOT?

If your vehicle was originally fitted with ABS, an illuminated ABS warning light can result in an MOT failure where it indicates a fault with the system.

ABS is an important vehicle safety system, so an ABS fault should be addressed rather than waiting until your next MOT.

If your MOT is approaching and the ABS light has recently appeared, arranging a diagnostic check beforehand can help identify and resolve the problem.

Does the ABS Light Mean My Brakes Have Failed?

Not necessarily.

One of the most important things to understand about the ABS warning light is that an ABS fault and complete brake failure are not necessarily the same thing.

If only the ABS light is illuminated, your conventional brakes may continue to work.

However, the anti-lock function may be unavailable.

This means you could have less control during heavy or emergency braking, even if the brake pedal initially feels normal.

If the brake warning light is also illuminated, or the vehicle's braking performance has changed, seek professional assistance.

What Happens If You Ignore the ABS Light?

It can be tempting to ignore an ABS warning light if your car appears to be driving normally.

However, doing so means you may not have the full benefit of the vehicle's safety systems when you need them.

Ignoring the problem could also allow a relatively straightforward fault to develop into a more expensive repair.

If the ABS light remains illuminated, getting the vehicle checked promptly is the safest approach.

Can an ABS Light Come On Because of a Flat Battery?

Low battery voltage or an electrical issue can sometimes cause multiple dashboard warning lights to appear.

This can include ABS-related warnings.

If the ABS light appeared after a flat battery, jump-start or battery replacement, restarting the vehicle may clear a temporary warning.

If the ABS light stays on, however, the system should still be checked.

Can You Reset the ABS Light?

It may be possible to clear an ABS warning light using diagnostic equipment.

However, simply resetting the ABS light without fixing the underlying problem is not recommended.

If the fault remains, the warning light is likely to return.

The better approach is to identify the cause of the warning, repair the fault and then clear the stored fault code where appropriate.

ABS Light Frequently Asked Questions

What does the ABS light mean?

The ABS light indicates that your vehicle's Anti-lock Braking System has detected a fault. Your standard brakes may still work, but the anti-lock function may be unavailable.

Why is my ABS light on but my brakes work?

The conventional braking system can continue to operate even when the ABS has developed a fault. However, you may not have the additional safety benefits provided by ABS during heavy braking.

Is it safe to drive with the ABS light on?

If only the ABS light is illuminated and your brakes feel normal, you may be able to drive cautiously to have the vehicle inspected. However, the ABS system may not function correctly. If the brake warning light also appears or braking performance changes, stop when safe and seek professional assistance.

How do I fix my ABS light?

The correct repair depends on the cause. Common ABS faults include faulty wheel speed sensors, damaged reluctor rings, electrical problems, low brake fluid and ABS control module or hydraulic unit faults. A diagnostic check can identify the cause.

How do I turn off the ABS warning light?

The ABS warning light should not simply be switched off without diagnosing the problem. Once the underlying fault has been repaired, diagnostic equipment can usually clear the warning.

Can low brake fluid cause the ABS light to come on?

Low brake fluid can cause braking-system warning lights to appear and may be associated with ABS warnings on some vehicles. A low fluid level should always be investigated.

Is an ABS sensor expensive to replace?

The cost varies depending on the vehicle and the particular component that has failed. A diagnostic check should be carried out first to confirm that the ABS sensor is actually responsible.

Will an ABS light fail my MOT?

An illuminated ABS warning light indicating a fault can result in an MOT failure on vehicles fitted with ABS. It's best to have the issue diagnosed before your MOT.

Get Your ABS Light Checked at Sandicliffe

Your vehicle's Anti-lock Braking System is an important part of its safety equipment.

If the ABS light comes on, don't ignore it simply because the car appears to be driving normally. While an ABS fault does not necessarily mean your conventional brakes have failed, it can mean the anti-lock function is unavailable when you need it most.

At Sandicliffe, our technicians can use specialist diagnostic equipment to identify ABS faults and investigate potential issues with sensors, wiring, braking components and the ABS system.

If your ABS warning light is on, arrange a professional inspection and get your vehicle's braking system checked.

Book your vehicle in with Sandicliffe today and drive with confidence.