What it means
Same as P0555 with the signal voltage above the plausible range. Boost control tracks commanded vs. actual manifold pressure; persistent deviation means wastegate, vanes, hose or actuator are not delivering the requested pressure.
At a glance
- Usually lights the check-engine light
How it works
The brake-booster pressure sensor sends a signal to the control module so it can assess pressure available for brake assist. P0558 sets when the sensor signal rises above its calibrated electrical range, often because the signal is shorted to a voltage source; it does not alone establish that booster pressure is excessive.
Common causes
Most likely first.
- Signal shorted to supply
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check-engine light may come on
- Cruise control may not engage or may disengage
- Brake assist warning may appear
- Braking may feel harder if booster assist is affected
How to diagnose it
- Save freeze-frame data and check live brake-booster pressure and related warnings to identify when the signal goes high.
- Inspect the sensor connector and harness for corrosion, pin damage, or wiring pinched against a power source.
- Check the signal wire for a short to voltage and test circuit continuity against the manufacturer's specification.
- Verify sensor power and ground connections against the manufacturer's specification.
- If the wiring and connections pass, test the brake-booster pressure sensor against the manufacturer's specification.
Common fixes
- Secure or repair a loose, corroded, or damaged sensor connector.
- Repair wiring pinched or chafed against a voltage source.
- Repair a signal circuit short or open.
- Replace the pressure sensor if it fails testing.
Can I keep driving?
Because brake assist may be affected and the pedal can become harder to press, avoid unnecessary driving; stop if braking effort increases or a brake warning appears. Have the fault checked promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.