What Causes Brakes to Lock Up While Driving? – 5 Reasons

Written by

Charles Bolte


Vernon Hoppe 

what causes brakes to lock up while driving

Brakes play a vital role in cars and in driving as it is used to reduce speed or completely halt to avoid accidents. It is easy to assume that everything is running smoothly until you hit the brakes and nothing happens because of brakes randomly locking up.

So what causes brakes to lock up while driving? This means your ABS is failing and has issues with its brake components such as brake pads, calipers or brake fluid in the master cylinder.

Why are Brakes Locking Up While Driving?

So why are my brakes locking up? Here are the most common causes:

1. Issues with the Anti-lock Braking System


Cars equipped with the Anti-lock Braking System or ABS is very important as it keeps the front brakes of your car from locking up and allows you to keep control of the vehicle. By doing so, you are able to steer away from obstacles or other vehicles from crashing.

Should your brakes lock up, your ABS will flash on your vehicle’s dashboard indicating that the system is malfunctioning. This could mean that there are serious issues with its wiring, sensors, valves, pumps or the electronic control unit, all of which composes the ABS to function.

It is crucial to have it checked by a professional mechanic, since malfunctioning ABS brakes is a matter of concern as it involves the safety of the user and/or the passengers.

2. Hydraulic Fluid Issues


Hydraulic fluid issues such as improper brake fluid or low brake fluid can also be a factor which can cause locking up on car brakes. It is triggered by a push on the brake pedal allowing the fluid to push through its way to the calipers and produces friction for a car to stop.

Keep in mind to use the brake fluid that would be compatible with your car’s system, as the usage of an incompatible brake fluid is prone to moisture build-up that can affect the performance of your front disc brakes and rear drum brakes negatively.

The DOT 5 Brake Fluid is a silicone-based fluid, but does not absorb any moisture and is used in older vehicles without the ABS. While the DOT 3 and DOT 4 Brake Fluid can absorb moisture and prevents problems with your brake system such as rusting.

Check your brake fluid and make sure that there are no leaks, as it can also cause brake calipers locking up. It is advised that brake fluids are flushed every two years or around 30,000 miles.

It can also be dependent on the user’s driving routine and driving conditions as to when brake fluids need to be flushed, considering dust and moisture have not found its way through the master cylinder.

Therefore it is also important to go through your vehicle’s manual for other specific instructions and information.

3. Damaged Brake Mechanical Components


Check the condition of your car’s mechanical components such as the brake pads, pedals, rotor, brake caliper and drum brakes. Make sure that they are not rusted, worn out or deformed. Brake pads last about 50,000 miles.

For brake pedals, make sure that vacuum hose has no problems or leaks because it can make a brake pedal hard and brakes lock up upon stepping on them.

Cars that have not been used for driving for more than two weeks cause the rotors and brake calipers to be rusty and subject to corrosion especially while parked on outdoor terrain where natural forces can occur.

You should be able to tell if you have faulty brake components, when your braking produces unusual, squeaky sounds, or throbbing sounds when brakes are applied while driving.

4. Problems with the Master Cylinder and Worn Out Piston Seal

The Brake Master Cylinder generates the pressure, as it is responsible for the overall braking performance of a vehicle. It is also known as the heart of your vehicle’s brake system.

A faulty master cylinder can cause a fading or spongy brake pedal. This would affect the efficiency of the braking performance of a vehicle.

A damaged or worn out piston seal in a master cylinder can also cause leaks in the brake fluid, which again, can cause problems in braking.

5. Overheated Brakes


Too much friction can cause overheating in the car’s braking system. It is essential that brake pads are properly installed, and that the other brake components are in good quality so as to avoid overheating.

Brake calipers locking up can also cause overheating which may reduce the capability of your brake system to reduce the speed of your vehicle. Aggressive and overuse of brakes also causes the heat up of your brake discs for up to 600 to 700 °C.

What Does It Mean When Brakes Lock Up?

Brake lock up means that your ABS is failing, and that the moment you step on your brake pedals, your vehicle does not reduce its motion (kinetic energy) but continues to move forward unless an outside force puts it to a halt.

This could also mean that your car’s braking power has deteriorated.

Another factor is that you are putting too much force on your brake pedals, especially if your vehicle does not have the ABS. This can cause skidding on the road as you lose control of your vehicle.

Brake lock up is a serious matter, because of the fact that this can cause wreckage to your car and even accidents on the road.

How to React With a Lock-Up?


  • First thing to do is to remain calm and avoid freaking out as you won’t be able to focus and eventually lose control not only of your car but also of your emotional and mental state.

Check that your seatbelts are properly fastened as it would protect your body from serious injury in the event of an unlikely crash. Should you have passengers, also inform them to fasten your seatbelts for their safety.

  • Look for a safe area or place to pull over, as you do not want to continue driving your vehicle with a compromised braking system. You can check your braking system and if it is totally damaged you can have it repaired by calling towing services.
  • Should there be a crash, it is important to check yourself for any kind of injuries, call for help, and report to the police for more serious accidents. You can tend to minor injuries if you have an emergency kit nearby.

How to Fix Locked Up Brakes?

As you have learned earlier, the braking system has many components. It is recommended to inspect and identify first what part of the braking system has been compromised.

Faulty components may need replacement such as rusty rotors. For brake pads, if it becomes too thin, it will malfunction.

It is essential to confirm any issues with the master cylinder as well, including its brake fluid if there are leaks, or if they are in need of replacement due to incompatibility.

You can opt to call for a professional mechanic should you have problems which you think are beyond your limits, so that your vehicle can receive the proper servicing and repairs.

Frequently Asked Questions


How Do You Know If Your Brake Line is Clogged?

You will know if your brake line is clogged mainly because when applying the brakes, your vehicle is not slowing down.

Another factor is that there could be a leak in your brake fluids or your brake pedals have an unusual sound or response when stepping on them.

Can I Drive With a Seized Brake Caliper?

If your brake caliper is stuck or won’t move, then it is not advised to drive your vehicle. Since your brake caliper is compromised, your braking system may not function properly as it is unable to disengage the brakes in the rotors.

This will give you difficulty to control your vehicle and can cause accidents. Continued usage of brake pads and calipers will damage it even more.

How Much Does It Cost To Fix It?

Repairs and replacement may differ on the braking component that has been worn out. A repair of the master cylinder can cost you $200 to $300.

Brake caliper replacement can cost between $250 -$750, while brake pad replacement can be around $130-$400. On the other hand, fixing an ABS can go around $300-$1000.


So the reason why your brakes keep locking up is due to a malfunctioning ABS. Therefore it is best to make sure our cars are frequently inspected for any kind of damage and have worn out materials and components replaced to avoid road mishaps.

We hope that we have answered the question on what causes brakes to lock up while driving. Feel free to give us your thoughts and share this article to your friends.

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