P0558 — Brake Booster Pressure Sensor Circuit High Input
Moderate severityWhat it means
P0558 is stored when the engine control unit sees a fault involving the brake booster pressure sensor circuit. The brake booster pressure sensor lets the control unit confirm there is enough vacuum or pressure for power-assisted braking, and run the auxiliary vacuum pump if fitted. A “high” reading means the signal is pinned near the top of its range — often an open circuit, a lost ground, or a short to voltage.
Common symptoms
- The live reading sits abnormally high or maxed out
- A firmer brake pedal in some cases
- Brake or auxiliary-pump warning
- Check engine light
Likely causes
- Open signal or ground wire
- Signal wire shorted to a voltage supply
- A faulty brake booster pressure sensor
- A vacuum leak or a wiring/connector fault
What to check first
- Check for an open circuit or missing ground at the sensor connector
- Compare the sensor reading with actual booster vacuum
- Inspect the sensor, hose and connector
Can you keep driving?
Braking is power-assisted, so take this seriously — if the pedal feels hard, have it checked before driving far.
Frequently asked questions
What is the most common cause of P0558?
The most likely cause is: Open signal or ground wire. Several other faults can set P0558 as well, so confirm the real cause with live data and the checks above before replacing any parts.
Can I just clear P0558 and keep driving?
Clearing P0558 with an OBD2 scanner turns the warning light off, but if the underlying fault has not been repaired the code will usually come back within a few drive cycles. Fix the cause first, then clear the code to confirm the repair worked.
How serious is P0558?
P0558 is a moderate-severity code. The car is often still drivable, but have it diagnosed soon — the underlying problem can get worse and it may fail an emissions test.
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