Symptoms of a Bad or Failing Power Brake Booster

The purpose of a brake booster is to provide power assistance to the braking system, meaning you do not have to put a lot of force on the brakes for them to actually engage. The brake booster is located between the brake pedal and master cylinder and uses a vacuum to overcome the fluid pressure in the brake system. If your brakes are not working properly, the vehicle should not be driven. The brake booster is an essential part of the braking system, so keep an eye out for the following 3 symptoms so you can have them repaired right away:

1. Hard brake pedal

The primary indicator of a bad brake booster is an extremely difficult-to-push brake pedal. This issue may occur gradually or appear all at once. In addition, the brake pedal will not return to its original position after being pressed. As soon as you notice your brake pedal is hard to engage, contact a professional mechanic to have your brake booster replaced. It is critical that brake booster faults are repaired quickly — the car is not safe to drive with a failed brake booster.

2. Longer stopping distance

Along with a hard brake pedal, you may notice it takes the vehicle longer to actually stop. This is because you are not getting the actual power boost needed to properly stop the vehicle. A longer stopping distance can be hazardous in all types of weather because it can make your car unpredictable. This issue should be looked at by a mechanic as soon as you notice it.

3. Engine stalls when brakes are applied

When the brake booster is failing it can draw excess vacuum from the engine. This occurs when the diaphragm inside the brake booster fails and allows air to bypass the seal. The brakes are then pressed, the engine feels like it will stall, and the idle can drop. In addition to the decreased brake performance, a stalling engine can cause serious issues.

Test the Booster

Since most vehicles use a vacuum system, the brake booster can be tested at your home. Observe the following 3 steps:

  1. With the engine off, pump the brakes — about five or six times is sufficient. This depletes the stored vacuum.

  2. Turn the engine on while pushing down lightly on the brake pedal. If your brake booster is working normally, the pedal will fall away a little, but then become firm.

  3. If your brake booster is not working correctly, nothing will happen, or the brake pedal will push back against your foot once the engine starts. This could be a sign of a brake booster problem or an issue with the vacuum hose.

If you notice the brake pedal is difficult to push, higher than normal, and your vehicle takes longer to stop, have a mechanic inspect it to be safe on the road. If needed, the mechanic will replace your brake booster in a timely manner so you can safely drive your vehicle again.


Next Step

Schedule Brake System Inspection

The most popular service booked by readers of this article is Brake System Inspection. Once the problem has been diagnosed, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Brake System Inspection reviews

Excellent Rating

(301)

Rating Summary
280
12
3
1
5
280
12
3
1
5

Johnny

33 years of experience
264 reviews
Johnny
33 years of experience
Toyota RAV4 L4-2.4L - Brake System Inspection - Sacramento, California
Johnny arrived early which was great, he performed the inspection in less than half an hour, and gave us a complete quote for all items needing attention, including the brakes as our main concern. Johnny is fast and efficient so I scheduled the work done by him.
Ford Escape - Brake System Inspection - Sacramento, California
The convenience is worth the cost. I was also tired of the dealership not really caring about my old car. Last couple of times I had to wait well over an hour to get my car after the dealership said "It's ready!". They also wouldn't fix the things I asked saying they didn't have time and I need to come back.

Jay

37 years of experience
947 reviews
Jay
37 years of experience
Chevrolet C10 Pickup V8-5.4L - Brake System Inspection - Moreno Valley, California
Knowledgeable, Professional, Friendly, and PATIENT! Sickeningly HONEST, as I tried to ply him with cash, alcohol, outside work, and wild dancing girls - although I wouldn't have "ratted him out" if he HAD accepted. A guy like this needs a "bigger cut" than what you are paying him ... because loyalty like his is hard to find these days! THANKS!
Volkswagen Jetta - Brake System Inspection - Moreno Valley, California
As usual, Mr. Jay provides efficient and professional quality of work. I would highly recommend him to any customer searching for a good mechanic.

Christopher

10 years of experience
114 reviews
Christopher
10 years of experience
Ford Explorer V6-3.5L - Brake System Inspection - Katy, Texas
Christopher was very knowledgeable and was able to address our concerns. We would trust him with future service needs.

Jesse

16 years of experience
61 reviews
Jesse
16 years of experience
Nissan Frontier V6-3.3L - Brake System Inspection - Flagler Beach, Florida
Jesse took the time to explain everything that was going to be done and why and then proceeded to repair my truck not only professionally but quickly. As a disabled Veteran and no longer able to perform work that was needed to be done it is nice to know a mechanic such as Jesse will take the time to explain all the various issues and what needs to be done before a blanket you need everything. After Jesse went thru everything I felt comfortable that all work was required and needed. 8 can safely say I will use yourmechanoc .com again and hope I can request Jess

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

How to Replace a Cruise Control Brake Release Switch
The cruise control is turned off by the brake release switch which fails either when the cruise control does not deactivate or does not set properly.
How to Replace an Anti-Lock Brake System (ABS) Fuse or Relay on Most Cars
Anti-lock brake systems have a fuse that fails if the ABS brake light is on or when the fuse is blown. The wheels may lock up if the ABS fuse is bad.
How to Replace a Vacuum Brake Booster
The vacuum brake booster generates extra force for car brakes. If your car is hard to stop or wants to shut off, replace your brake booster.

Related questions

Vibration in car body when in Drive
A few different items can cause the vehicle to have a vibration. The most likely would be a misfire, engine mount (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-engine-mount), or transmission mount. Most vibrations have a RPM range at which they are most noticeable. Increasing the idle...
hi how long should my brake calipers last?? based on other mercs etc
Brake calipers, associated torque plates and sliding pins should all be thoroughly cleaned and rebuilt every time you have to change the brake pads (https://www.yourmechanic.com/services/brake-pads-replacement). These parts are subject to corrosion, brake grit, dust and dirt, and extremely high heat....
Brake pedal stuck to floor - 1972 Volkswagen Super Beetle
Hello. There is a return spring on the assembly that must be dislodged or broken somehow, and when this happens there will be issues with the pedal returning. Have the pedal assembly and the hydraulic portion of the system inspected...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com