Symptoms of P0558
- Unstable, high, or low idle, or stalling.
- Erratic speedometer, cruise-control, or shift behaviour.
- Check-engine light with a hesitation or surge.
Common causes of P0558
- A dirty throttle body, idle-control valve, or throttle-position sensor.
- A failing vehicle-speed or wheel-speed sensor, or its wiring.
- Vacuum leaks or a related sensor forcing the idle/speed strategy.
Useful checks before replacing parts
- Review sensor voltage, reference voltage, ground path, brake pedal input, booster vacuum, engine load, and freeze-frame conditions.
- Inspect for open grounds, short-to-voltage faults, connector corrosion, vacuum supply problems, failed check valves, and sensor internal faults.
- Compare readings with no pedal input and repeated brake applications to determine whether the signal is stuck high or reflecting actual pressure loss.
Related OBD-II codes
These nearby speed / idle entries can help compare wording and pin down the fault area.