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?

Need advice from certified mechanic? Get help now!

Over 1,000 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
  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: Rebuilding transmission on a '94 Nissan Sentra

If it doesn't burn much oil, runs good, and is not a rust bucket like up North where everything is rust, then sure why not. My advice is that you are often better buying a remanufactured transmission factory remade and...

Q: The vehicle sputters and hesitates after being started on humid days.

Hi there. Depending on where you live, the introduction of humidity in the air will also affect the air pressure around your vehicle. Higher altitude areas are impacted greater when barometric pressure changes. When air pressure is affected, engine vacuum...

Q: Door handle not working

A common issue on the Accords is that the door latch wears out, and no longer opens with either handle. The door panel will have to be removed, and the door latch manually opened with a pick tool. This repair...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...