Why is my brake pedal soft?
A newly soft or sinking brake pedal can indicate loss of hydraulic pressure, fluid leakage, air, hose expansion, or a master-cylinder fault. It requires physical brake inspection.
Plausible causes
- External hydraulic leak
- Air or vapor in the hydraulic system
- Master cylinder or flexible hose fault
Useful next checks
- Keep the vehicle parked securely
- Look only for visible fluid without crawling underneath
- Have brake pressure and leakage tested professionally
Sources and method
This answer provides hypotheses and a verification plan, not a component verdict. Exact repair procedures require authoritative service information for the specific vehicle.
NHTSA vPIC Vehicle APISAE J2012