Brakes and steering
Soft, long or sinking brake pedal: what to do
If the brake pedal feels spongy, goes down further than normal or slowly sinks while you hold it, the hydraulic system has lost effectiveness: air, a leak, degraded fluid or the master cylinder. It is a safety fault.
Stop as soon as it is safeBrakes and steering
Reviewed by Daniel Morales, founder of Reprorace SL, on
Is it serious? Can I keep driving?
Do not keep driving. Do not drive: braking can fail when you need it most. If it happens on the move, shift down, brake with more travel, use the parking brake carefully if needed and stop where it is safe. Call for assistance.
A careful, general answer: only someone who inspects the car can say whether it is safe to drive. When in doubt, stop somewhere safe and call for assistance.
Most likely causes
- Fluid leak: in a hose, a caliper, a wheel cylinder or a pipe.
- Air in the system: after a badly bled repair or through a leak.
- Degraded or boiled fluid: with moisture absorbed or after long descents with heavy braking.
- Master cylinder: its internal seals let fluid by and the pedal sinks.
Listed from more to less common in general; on your car they may be different. A fault-code reading and a check at the garage confirm which one it is.
To understand it better: Can I diagnose my car myself? How often should you run diagnostics on your car?
Car system: Brakes, ABS and ESC
What you can check yourself
With the car parked, check the brake fluid reservoir level.
Look for damp patches near the wheels or on the ground under the car.
Check whether the red brake warning light has come on.
If the pedal is hard rather than soft, it may be the brake servo: that too must be checked before driving.
Safe checks only: with the engine off and cold whenever you look under the hood, without taking anything apart and without touching hot or moving parts.
Related fault codes
- C0045Brake pressure sensor B: malfunction
Generic codes that often come with this symptom. Seeing one does not confirm the cause: it is where the diagnosis starts.
How the ECO-LITE helps diagnose it
Plugged into the OBD socket, the ECO-LITE reads the fault codes of the control units that answer, with the freeze-frame data captured when the fault happened, and shows live data on your phone or computer. With your permission, your garage can see them remotely before you bring the car in.
What to look at here: ABS control unit codes and brake pressure if the car reports it; the fault is hydraulic and is confirmed on the car.
Frequently asked questions
Is it normal for the pedal to go soft after a mountain descent?
No: it means the fluid got too hot. Stop, let it cool and have the fluid checked; on descents use low gears.
Can I top up the fluid and carry on?
No: if fluid is missing, there is a leak or very worn pads. The cause must be found before driving.
What if the pedal is very hard?
A hard pedal that barely brakes usually means a fault in the brake servo or its vacuum: that is urgent too.
Keep reading
- Brakes, ABS and ESC: how they work and what fails
- Red brake warning light on: what it means and what to do
- Noise when braking: what a squeal or a metallic grinding means
- ABS or ESP warning light on: what it means and what to do
- Car symptoms: what they mean and what to do
- Check engine light on: what to do
- How to read and clear your car's fault codes
- OBD fault codes: what each one means