5 Reasons Why Brake Light Comes On While Driving

My brake light comes on while driving, what could be the reason? Brake lights indicate that your brakes are malfunctioning. You need to immediately stop the car and inspect it for reasons. The article below will help you diagnose the problem.

Brakes are essential for your vehicle. They keep you safe while driving your car on the road. Whenever you press the brake pedal, the force exerted is insufficient to create enough braking pressure. 

That’s why hydraulic brake fluid is used in most vehicles to amplify the force you apply on the pedal. Consequently, your car stops comfortably.

But sometimes, the brake warning light suddenly comes on while driving. It is an indication that there are issues in the braking system, and it needs to be corrected as soon as possible.

The brake warning light looks different on different models of cars. For example, some cars display a warning brake light as a circle with a semicircle on either side and an exclamation mark on the center. Other vehicles display a warning brake light in red color that says brake.


Brake Light Comes On While Driving


There can be numerous reasons for turning the brake light on. For instance, if the brake pads have become too thin or damaged, it disturbs the entire braking system. Similarly, if there is low brake fluid in the reservoir, the brake warning light may turn on in the dashboard.

Let us talk about the potential reasons why your brake light comes on while driving. Keep reading to get all the information.

Why Does Brake Light Come On While Driving?

#1. Low Brake Fluid

The brake fluid plays a crucial role in stopping your vehicle. When you press your brake pedal, the brake fluid from the reservoir enters the master cylinder and gets compressed. 

The high-pressure brake fluid then moves into the caliper and exerts a force on the brake pads, finally touching the rotor or disc and stopping your vehicle.

A sensor is usually there in the master cylinder, which evaluates the brake fluid level in the reservoir. If the brake fluid in the reservoir is less than the minimum value, then the sensor gets triggered and the brake light comes on when braking.This is also the reason why your brake light comes on when turning.


Fill the reservoir with brake fluid as soon as possible.

#2. Worn Out Brake Pads

Brake pads consist of steel plates and have friction lining on both surfaces. Whenever you apply brakes, they contact the disc or rotor and stop your car. When these brake pads get thinner or worn out, the brake light comes on when driving.


Replace the brake pads as soon as possible. You can even easily change the brake pads at home.


You might like to read: Where Is The Electronic Brake Control Module Located?


#3. Parking Brake Engaged

If you have left your parking brakes engaged while driving, it could be one of the reasons why your brake light comes on when driving. If your parking brakes are still engaged and you are driving, then the sensor in the parking brake will trigger the brake warning light to switch on.


You need to disengage the parking brake before driving. Driving with active parking brakes will overheat the braking system, and cause wear and tear very quickly.

Brake Light Comes On While Driving

#4. Anti Lock Braking System Malfunction

The antilock braking system in vehicles prevents the wheel from locking up when you are braking on slippery surfaces. It offers traction on the road surface and allows the driver to have more control over the car. 

The ABS mechanism helps control the vehicle on wet roads and slippery surfaces. The main aim of the ABS is not to stop the vehicle suddenly but to make sure that the wheels don’t lock up, causing the steering to lose control over the car.

If you are wondering: “why is my brake light blinking”, issues in the anti-lock braking system might be triggering the brake warning light or ABS light while driving. Some of these problems include a malfunctioning pump, controller, or speed sensors on the wheel.


Take your vehicle to the nearest mechanic. He will review all the ABS components of your car and correct them.

#5. Fault In Brake Light Bulb

Some vehicles monitor the rear brake light bulb. If it goes dim, then the brake light comes on when braking. Drivers are unaware of the brake light bulb at the back of the car. So, turning on the brake light will alert the driver that their brake lights are not working properly. The driver should get the bulb repaired at the earliest to prevent collisions.


Take your vehicle to the mechanic. He will detect the fault in the light bulb and may replace the bulb with a new one.


You might like to read: Brake Lights Wont Work When Headlights Are On


Frequently Asked Questions

#1. What does it mean when the brake light comes on while driving?

When your brake light comes on while driving, it indicates the following thing.

  • The low brake fluid in the reservoir
  • The emergency brake is activated
  • There is trouble with the Anti-lock braking system
  • Issue In Sensors


Brake Light Comes On While Driving


#2. What two reasons would cause your brake system warning light to come on?

  • Engaged parking brake
  • The low brake fluid in the reservoir

#3. Why does the brake light come on and off while driving?

If the brake light comes on and off while driving, there is extremely low brake fluid in the reservoir or a problem in the hydraulic brake system.

#4. Why Is My Brake Light Flashing On My Subaru?

  • The emergency brake is engaged
  • The brake fluid is leaking
  • The parking brake is activated
  • Brake lights are faulty


You might like to read: Why Do My Brake Lights Stay On: 5 Reasons And 7 Solutions


#5. Why Does My Brake Light Come On And Off?

The brake light comes on and off because your brake fluid is low or there are issues in the hydraulic system which need to be inspected and corrected immediately.

#6. What does service brake assist mean?

Modern day cars have a special safety function that lets the car come to a quick stop in an emergency. It is able to intelligently detect the warning signs of an emergency brake, and bring the car to a dead stop almost immediately. This system is known as service brake assist.

#7. Nissan Altima brake light comes on when accelerating?

It could be any car for that matter, not just a Nissan Altima. In most cases, the brake light coming on in any situation is because your brake fluid level is less than optimum.


Brake Light Comes On While Driving


A Few Final Words

Brakes components should always be in the best of conditions while driving. If you find your brake lights turning on while driving, I strongly advise you not to drive. Stop the engine in a safe area and inspect the braking fluid reservoir.

If you find that the brake fluid is low or empty, fill it with brake fluid. Then start the engine. If the brake light gets turned off you are good to go.

If the brake lights are still on after topping up brake fluid, some other components may  be malfunctioning in the braking system. It would be best to take your vehicle to the nearest mechanic. He will inspect your vehicle thoroughly and correct it. Thank you for reading the article and hope we were able to answer your queries.

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Sean Mendez

Hi, I am Sean, a self-confessed petrolhead. I live in Boise, Idaho with a busy family of four and our energetic Labrador retriever. Thank you for visiting my website. You can find my email on the contact page.

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