Skip the auto shop - Our mechanics make house calls

Q: Brakes hiss when I use them

asked by on

The ABS light has been on for a few weeks in my 2007 Camry V6 that I have driven for around 104,000 miles, and there's a hissing sound when I apply the brakes. I had my brakes and rotors changed last week by my mechanic friend, and I still was having the same issues. Today, the brakes lost power and it's like having old school manual brakes. Help, please.

A: Well, it sounds like you may have a vacuum ...

Well, it sounds like you may have a vacuum leak coming from the brake booster. I definitely recommend you do not drive the vehicle until you have an independent mechanic look over it, as this is a major safety concern. Typically when you will hear a hissing sound from applying the brakes, or if you hear the sound but the hissing noise goes away when the brakes are applied, it is a very good indication that the diaphragm in the brake booster is failing. The diaphragm allows air to escape the system and thus makes it harder to apply the brake pedal when it is failing. In addition to this, a bad or failing brake booster can be a symptom of another hidden problem, which is known as a leaking master cylinder. Now these two issues don’t always go hand in hand, but they often can and a certified technician will be able to determine if the master cylinder is leaking by separating the master cylinder from the vacuum brake booster and inspecting the cavity in the vacuum brake booster for signs of brake fluid. Brake fluid can eat away at and break down the diaphragm inside the vacuum brake booster as well. Before a repair is attempted, a diagnostic scanner is used to communicate with the ABS computer to determine if the warning light is related to this primary concern. If it is the case, the diagnostic scanner is used to clear the code from the computer and you can have the power brake booster is replaced. If that is not the case, further diagnoses will be needed to identify the problem.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Engine light on

Hi there. A code P0401 indicates that the EGR system is not working properly. The EGR, or exhaust gas recirculation system, is used for emissions to reduce the NOX emissions. If it's not functioning and opening as it should, then...

Q: My car does not have an immobilizer installed on it, but it is keeping my 2007 Honda CRV from starting.

Hi there. If your vehicle is not equipped with the immobilizer system, but yet it is causing your vehicle not to start, then there is a problem with the engine control module. Most of the time the module can be...

Q: Hey! My brake light has come on. This is my first time owning a car and I'm not sure what to do or what is the problem.

The best thing to do is to have a mechanic like one from YourMechanic come to you and check the vehicle to see what brake light is on red brake one or yellow ABS one. If it is the red...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...