P0558

Universal

Brake Booster Pressure Sensor Circuit High Input

Definition source: General OBD-II reference catalog
Definition verification: Not independently verified for display.
Time: Varies by diagnosis and vehicle | Diagnostic difficulty: Medium
High Severity

The vehicle detected a signal that is higher than expected in the brake booster pressure sensor circuit. This sensor provides information about pressure related to brake assist, which helps reduce the effort needed to press the brake pedal. The code identifies an electrical signal condition; it does not by itself prove the sensor has failed. Depending on the vehicle and the underlying cause, brake assist may be reduced or the code may have no noticeable effect.

Report an error with this code

⚠️ Before You Begin (Safety First)

If the brake pedal becomes unusually hard, braking feels reduced, or a brake warning appears, stop somewhere safe and arrange for qualified inspection; do not continue driving if you cannot brake normally. If braking feels normal, have the fault diagnosed promptly and follow any vehicle-specific warning messages.

Common Symptoms

  • There may be no noticeable symptoms if brake assist continues to operate normally.
  • The brake pedal may feel harder to press if brake assist is reduced.
  • Stopping may require more pedal effort, depending on the vehicle and the underlying fault.
  • A warning light or stored diagnostic code may be present.

Common Causes

  • A pressure sensor may be producing an abnormally high signal or may have an internal fault.
  • Damaged wiring or a short to a power source may raise the circuit signal.
  • A loose, damaged, or corroded connector may disrupt the sensor circuit.
  • A circuit ground, power supply, or control-module issue may affect the reported signal.
  • A brake-assist pressure or operating problem may contribute, depending on the vehicle design.

Diagnostic Steps

  1. Note any brake warning messages and whether pedal effort or braking has changed. If braking feels impaired, stop driving and arrange for inspection.
  2. With the vehicle safely parked and the ignition off, look for visible damage, looseness, or corrosion on accessible wiring and connectors associated with the brake booster pressure sensor. Do not probe connector terminals or disconnect components unless the vehicle-specific procedure says it is safe.
  3. Check the owner’s manual for the meaning of any brake-system warning and follow its instructions.
  4. If you have a scan tool, record the code and any related codes before clearing anything. A code alone does not identify which component has failed.
  5. Have a qualified technician test the sensor signal and circuit against vehicle-specific service information before replacing parts.

When to Call a Professional

A technician can review scan data and the circuit signal, then inspect the sensor connector and wiring and test the circuit using the vehicle-specific service information. The checks should distinguish a sensor problem from a wiring, connection, power, ground, or brake-assist system issue. Exact test points and expected readings depend on the model, year, and engine.

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Commonly Asked Questions

Does P0558 prove the brake booster pressure sensor is bad?

No. It indicates a high signal in the sensor circuit. Wiring, connectors, circuit power or ground, and other system issues can also cause that condition.

Can I drive with P0558?

If the pedal is unusually hard, braking feels reduced, or a brake warning appears, stop somewhere safe and arrange for qualified inspection. If braking feels normal, seek diagnosis promptly and follow the vehicle’s warning messages.

What does “circuit high input” mean?

The vehicle detected a signal higher than expected in the brake booster pressure sensor circuit. It describes the detected electrical condition, not a confirmed failed part.

Could the code appear without a change in braking?

Yes. A circuit fault may be detected before a driver notices a change, and some causes may not immediately affect how the brakes feel.

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