EngineLightCodes
Powertrain code

P0458 EVAP System Purge Control Valve A Circuit Low

Severity
Fix soon
Typical repair cost
$30–$220
Do it yourself
Possible, easy
Shop time
0.3–1.5 hours

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.

How the engine computer detects it

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 energized and open all the time, purging is uncontrolled – rough idle, rich mixture or hard starting after refuelling are possible.

Written from public technical sources and not yet checked by a mechanic. How we write these pages

Symptoms

  • Check engine light on
  • Rough idle or rich mixture possible (valve permanently open)
  • Starting problems after refuelling possible

Common causes

  1. Purge valve control wire chafed against ground Most likely
  2. Purge valve coil shorted internally Possible
  3. Connector scorched or wet Possible
  4. Driver in the engine module Less likely

How to diagnose P0458

  1. Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
  2. Inspect the parts involved: evap purge valve, purge valve wiring, engine control module.
  3. Work through the causes above from most to least likely, cheapest checks first.
  4. Clear the code and drive a full drive cycle to confirm the repair held.

Vehicles that report P0458 most

VehicleYearsReportsMedian miles
Chevrolet Volt2016–20184—

Counts of owner complaints to the NHTSA that mention P0458 (4 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.

Reading the code

P
Powertrain
0
Generic (SAE) code
4
Auxiliary emission controls
58
Specific fault

Questions drivers ask

Can I drive with code P0458?

Usually yes for a short time, if the car drives normally, the temperature gauge reads normal and the check engine light is steady. If the light flashes, the engine loses power or overheats, or other warning lights come on, pull over and have it checked.

Will my car pass an emissions inspection with P0458?

Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.

Will P0458 clear by itself?

The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.

Can I fix P0458 myself?

Often yes, with an OBD-II scanner and basic tools. Difficulty: easy. Start with the cheapest checks before replacing expensive parts.

Often reported together

Codes that owners mention in the same NHTSA complaints as P0458. They can point to a shared cause, so it's worth checking them together.

This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.