P0458EVAP System Purge Control Valve A Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. Purge valve A is switched to ground by the module and fed from the main relay. P0458 means its control wire is shorted to ground: GM detects it with the driver off, when the line sits at ground instead of supply (20 of 25 samples, MIL after two trips); Saab's ME9 uses below 2.6 V at the output. The valve is then energised and open all the time, purging is uncontrolled – rough idle, rich mixture or hard starting after refuelling are possible.
- What you may notice
- Check engine light on
- Rough idle or rich mixture possible (valve permanently open)
- Starting problems after refuelling possible
- Likely causes
- LikelyPurge valve control wire chafed against ground
- PossiblePurge valve coil shorted internally
- PossibleConnector scorched or wet
- RareDriver in the engine module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €25 – €200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.