Q: Brake pedal sinks

asked by on

Brake pedal sinks, I added fluid, it wasn't very low.brakes was good before. It keeps taking fluid. I haven't seen any signs of leaks at calipers, master cylinder, or under dash. Pedal will feel good when sitting if I pump it. Once key is turned it sinks. And yes my check engine soon light comes on shortly after driving. Could this be the master cylinder?

My car has 82000 miles.
My car has an automatic transmission.

This is a sign of a potential vacuum leak in the brake booster. When there is not enough vacuum in the brake booster, this will cause a hydraulic pressure drop resulting in a soft brake pedal. If you’d like, a certified YourMechanic technician can come to your location and help you with a Brake pedal is lower than usual Inspection to confirm that this is the issue, and also help to perform a Brake Booster Vacuum Pump Replacement to repair this issue.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Brake pedal sinks

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: Serpentine belt keeps coming off

The pulleys will not just lose their alignment. For this to happen, there has been a failure somewhere. One of the most common causes I have found for this problem, on a serpentine belt system, is that the belt tensioner...

Q: The ignition in my car won't turn everything is locked up would I be able to replace the tumbler from one at the scrap yard ?

No you would not be able to use it since the keys are program keys. You will need to get a new one and then have it programmed to work with your car. You may be able to have another...

Q: Occasional difficulty reversing

Manual transmissions use synchronizers as buffers between the engagement of the gears. When a manual is difficult to get into reverse, it is either due to the reverse lockout failing or the reverse synchro being worn and taking a few...

Related articles

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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.