Common Signs and Symptoms of a Bad Brake Booster!

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The brake booster is one of the important parts of the braking system which helps to press the brake comfortably and makes the brake paddle soft. Uncomfortable brake paddle is always embarrassing and a bit dangerous. So, everybody should care about car brake systems.

If you feel little a problem at the brake system, it should be diagnosed. By doing this, you can find out what the actual problem is and you can solve it immediately. However, today’s topic is the symptoms of a bad brake booster. After finishing this article, you’ll get to know the most basic symptoms of a bad brake booster and how you can determine you have a bad brake booster.

We will try to share a few tips and tricks too! Those may help you.

So, let’s start!

Before we discuss our main topic Symptoms of a bad brake booster, we have to know how the brake booster works actually.

What is a Brake Booster

When we’re discussing the function of a brake booster, you may ask what the brake booster actually is, how does it look, no?

Well, here’s your answer. The brake booster is a thing that works with the master cylinder in order to give higher pressure to the brakes. It almost looks like a circular shaped canister which is black in color. It produces required pedal pressure required for braking too!

The location of this device is the backside of the engine case in between the master cylinder and the pedal. To balance the high fluid pressure in the braking system of a vehicle, it basically uses a vacuum. With this, it can perform an effective braking operation.

Now, let’s take a look at how a brake booster works.

Working Process of a Brake Booster

Basically, the brake booster comes up with two different types. The single type is for small vehicles and for bigger trucks and cars, there’s the tandem type. Their work is to multiply the force to the brake pedals. There’s a liquid that transmits the pressure to the brakes when a driver presses the brake pedal. The fact is, the given force is not enough to stop the vehicle sometimes. That’s why the brake booster multiplies the force to 2-4 times as per the size of the diaphragm.

When the driver gives pressure to the brake pedal, a shaft moves forward which is attached to the power brake booster. It moves with thrusting a piston toward the main brake cylinder. So, the brake liquid goes through the braking system and it gives the pedal much strength while keeping the braking system’s pressure balanced.

Symptoms of a Bad Brake Booster

Basically, there are three common symptoms of a bad brake booster you can notice. They are:

#01. Hard Brake Pedal:

This is the most common symptom of a bad brake booster. When you press the brake pedal, you may feel that the pedal is too much hard to press or you may notice that it goes back to its position slowly. If you feel something like this, you have a bad brake booster. It’s a clear symptom of a bad brake booster.

So, you need to fix it as soon as possible. Or else, your vehicle is not safe to drive. You must go to your reliable mechanic or reliable garage and replace the brake booster immediately. Don’t forget to have a checkup of the brake master cylinder while you’re replacing the brake booster.

#02. Increased Stopping distance:

Uncomfortable brake pedal makes your stopping distance increased. There are so many reasons for those, your brake distance may increase. Bad condition road or slippery road can make stopping distance increased too!

You must check out what the actual problem is and fix it as soon as possible by a good mechanic or a garage. You can learn more about braking distance formula.

#03. Engine stalls when braking:   

Sometime Brake booster diaphragms or seals fail. As a result, excess air comes through the brake booster and engine stalls when you’re braking. Sometimes, car shuts down its power when you’re braking.

So if you feel such a type of problem in your car, don’t ignore the issue. Fix it immediately. We always recommended doing car repairing works with a good and reliable garage.

The FAQ (Frequently Asked Questions)

Q: What are the signs of a bad brake booster?

A: There are three signs of a bad brake booster. If you see your engine stalls when you’re pressing the brake pedal, you have a bad brake booster. If you find out our brake pedal too much hard, you have a bad brake booster. Besides, if your stopping distance increases, maybe you have a bad brake booster.

Q: How do I know if my brake booster or master cylinder is bad?

A: If you feel a little bit of extra pressure on the brake pedal then there are chances that you have a bad master cylinder or there’s air inside the master cylinder and feel had to press the brake paddle. To determine the brake booster, read this article carefully.

Q: Can a bad brake booster cause a spongy pedal?

A: Yes, it can. When you press the brake pedal, you may feel a little spongy if you have a bad brake booster. The main reason for this is low pressure. When the pressure of the vehicle’s brake system reduces due to a bad brake booster, the brake pedals works softly or in a spongy way.

Q: Will a bad brake booster cause your check engine light to come on?

A: Some of the models have a brake booster vacuum sensor. This feature is quite rare. When there’s anything wrong at your brake booster, this sensor gives a signal to the central processing unit and it shows a Check light popping up.

Q: How much does it cost to replace a brake booster?

A: The average cost to replace a brake booster is in between $280 to $700. The price varies from models to models. We always recommend buying spare parts from reputed sources or from the sources recommended by the manufacturer.


So, these are the basic symptoms of a bad brake booster. If you feel any of these with your vehicle, you must have your vehicle checked up by a good mechanic. It’s almost a serious issue if you got a bad brake booster. You can’t stop the vehicle immediately. It can cause a dangerous accident and irreparable loss.

To read other articles like this one, visit our website. If you have any question remaining in your mind feel free to leave a comment here or contact us directly.

Happy driving!

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