Symptoms
- Brake pedal feels mushy or sinks further than normal before engaging
- May need to pump the pedal to get firmer braking
- Possible longer stopping distance
Likely causes
- CommonAir in the brake linesAir compresses unlike fluid, making the pedal feel soft instead of firm.
- CommonLow brake fluid levelOften from worn pads or a small leak somewhere in the system.
- PossibleOld brake fluid that has absorbed moistureBrake fluid is hygroscopic and degrades over time, softening pedal feel.
- PossibleLeak in a brake line, caliper, or master cylinderFluid loss reduces hydraulic pressure needed for firm braking.
- Less commonFailing master cylinderInternal seal wear can let fluid bypass internally, causing a spongy or sinking pedal.
What to do
- Check the brake fluid reservoir level against the min/max marks.
- Look under the car and near each wheel for signs of fluid leaking.
- Top off fluid if low, using the correct DOT-rated type, but treat this as temporary if a leak is found.
- Avoid driving if the pedal sinks significantly or needs pumping to work at all.
- Have the brake system bled by a mechanic to remove air if fluid is fine and no leak is visible.
- Have any leak repaired first, then have the whole system bled afterward.
- Ask about brake fluid age; if it hasn't been flushed in a few years, a fluid change may also help.
Tools and parts
Brake fluid, DOT rating from owner's manualSearch: “DOT 3 or DOT 4 brake fluid for your car”
When to call a pro
See a mechanic to bleed the brakes and check for leaks, especially if the pedal has gotten noticeably softer recently.
Safety
Use caution
If the pedal sinks toward the floor or needs pumping to stop the car, don't drive it until it's inspected; this can mean a serious loss of braking power.