P0458 code meaning
EVAP System Purge Control Valve A Circuit Low
Powertrain system Generic code P04xx codes Check engine light
What P0458 means
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.
P0458 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0458
- Check engine light on
- Rough idle or rich mixture possible (valve permanently open)
- Starting problems after refuelling possible
Common causes of P0458
- Most likelyPurge valve control wire chafed against ground
- PossiblePurge valve coil shorted internally
- PossibleConnector scorched or wet
- Less likelyDriver in the engine module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EVAP purge valvePurge valve wiringEngine control module
What each part of P0458 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 58 | The exact fault in that area. |
What to do next
- Note P0458 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0458
What does P0458 mean?
P0458 means "EVAP System Purge Control Valve A Circuit Low". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P0458?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0458 fail an emissions test?
Yes, it can. P0458 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0458 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0458 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.