What Does it Mean When ABS Light Comes On?

The anti-lock braking system (ABS) is an ingenious feature that prevents skidding when your tires lose traction. It is used on planes, cars, buses, trucks, motorcycles, and other types of land vehicles to maintain friction between the tires and the ground.

The ABS light comes on when there’s a problem with one or more of the components that make up the anti-lock braking system in your car. It could signal a defective wheel speed sensor, bad wiring, a faulty ABS control module, a damaged relay, low brake fluid, a blown fuse, a bad solenoid valve, or a faulty hydraulic pump.

Ideally, the car is designed to flash all the lights on the dashboard when you switch it on. This allows the computer to do a diagnostic check of all the systems. The lights, including the ABS light, turn on momentarily before going off, unless there’s a problem somewhere.

What is anti-lock braking system and how does it works?

The anti-lock braking system or ABS prevents the wheels from locking up when you slam on the brakes while driving on a slippery surface or during an emergency.

In a situation where ABS is not available, the brakes will stop the wheels from moving, causing them to “lock up.” Due to a lack of sufficient traction between the tires and the ground, the vehicle continues moving as the tires skid over the surface.

This can be dangerous as the driver may end up losing control of the vehicle due to the skidding effect. The anti-locking braking system prevents this by using sensors to monitor how fast each wheel is rotating.

When you slam on the brakes, the system can detect when the wheels suddenly stop moving and go on a skid. With the help of valves and pumps, the electronic control unit (ECU) applies and releases the brakes several times per second to stop the wheels from sliding.

The valves release pressure on the brakes as the pump supplies hydraulic fluid at high pressure onto the calipers or brake drums.

In summary, the system works in three steps:

  1. Driver slams on the brake pedal
  2. Wheel sensors communicate when the wheels lock and start to skid
  3. ABS applies brake pressure

The primary objective of the ABS system is to help drivers maintain control of their vehicle during heavy braking and in emergency situations. It is not meant to stop the car faster. However, it does help to reduce the stopping distance in ideal conditions.

When the ABS light comes on, it means that there’s a problem that is preventing the system from providing assistance when needed. Connect an OBD2 code reader to the car’s computer to scan any trouble codes. This will direct you to where the problem is.

What causes ABS light to come on and stay on?

As mentioned earlier, there is a myriad of reasons why your ABS light could come on and stay on. If you’re wondering why the ABS light is on, there are four common reasons that plague the systems.

1.     Bad wheel speed sensor

The wheel speed sensors are usually the first point of communication in the ABS system. They tell the car’s computer how the wheels are behaving.

If the computer detects an anomaly in the wheel speeds, it makes adjustments to the traction control system and activates ABS to compensate for the mishap.

However, if the sensor is dirty or damaged by road debris, it will not be able to relay accurate information. This will cause the ABS light to come on. You’ll have to replace the sensor.

2.     Faulty ABS module

The anti-locking braking system shares the same electronic control module as the traction control system. Sometimes, the two systems can interfere with each other if one of them has an issue.

In this case, problems with the traction control feature in your car can cause issues with the ABS. Most times, however, the problem is with the ABS system or the control module itself.

This is a job that requires a professional. Electronic control modules are usually expensive parts that costs several hundreds of dollars to replace. A certified mechanic will be able to diagnose it and find the problem.

3.     Low hydraulic fluid

The hydraulic brake fluid could be low in the master cylinder, hence, affecting how the ABS in your car applies pressure to your brakes.

The cylinder presses against the fluid to help close the brake pads. This helps to bring the car to a complete stop.

If the brake fluid is contaminated or low, it will not perform as it should. It may have evaporated or leaked from the lines.

Your car’s computer will be able to detect this and turn on the ABS light on the dash.

4.     ABS is off

Sometimes, the ABS light can come on to notify you that the system is off. You may have accidentally turned it off without knowing.

It is an important safety system that is designed to stay on at all times. Check to see if you accidentally flipped or pressed a switch that turned it off.

How do I fix my ABS light?


Here are some of the steps you can take to troubleshoot and fix the ABS light:

·       Reset the ABS system

Switch the car on and off at least three times and check if the ABS light will disappear from the dashboard.

This helps to reset the codes stored in the ECU. If it doesn’t work, you’ll have to take the car to a mechanic for a proper diagnosis.

·       Clean the wheel sensor

Use some electrical parts cleaner to remove dirt and debris from the front wheel speed sensors.

You’ll have to get to the wheel speed sensor first and remove it from the wheel. Consult your owner’s manual to find out how to do this. You can also check online.

·       Check the wiring

Open the hood of your car and check for corroded or loose wiring. Check underneath the car as well and inspect the connection that goes to the wheel speed sensors.

You want to see if the wires are damaged at any point. Check for signs of chewed parts which may be an indication of rat infestation.

·       Refill brake fluid

Check to see if there’s enough brake fluid inside the master cylinder. If it’s low, you’ll need to fill it up to the recommended level.

Be sure not to add too much as that can compromise the performance of your braking system. If the brake fluid is contaminated or old, bleed your brakes and change the fluid.

Is it safe to drive a car with ABS light on?

The ABS light could mean that your car is unsafe to drive especially on slippery surfaces. The system will not be able to restore traction when the tires start to skid.

It’s best to drive slowly and not to do any hard braking at high speeds. The system will not kick in to prevent wheel lockup.

A study conducted by NHTSA shows that nonfatal crashes have gone down by 6% in cars thanks to the ABS system.

This means that the feature is indeed useful and effective. Do not ignore the ABS warning light on your dashboard.

How much does it cost to fix ABS?

The cost of replacing an ABS wheel speed sensor ranges between $200 and $400 for each sensor. Parts typically cost $100 – $150 while labor will cost you $100 – $300.

The price for a new ABS control module ranges between $320 and $1,000 if not more. The price is driven by the type of car and the labor costs.


The anti-locking braking system is a very important safety feature in your car. When the ABS light comes on, it’s only prudent to have it checked as soon as possible. This ensures that you stay safe at all times, especially when driving on wet and slippery roads.