P0459 code meaning
EVAP System Purge Control Valve A Circuit High
Powertrain system Generic code P04xx codes Check engine light
What P0459 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. P0459 means its control wire is shorted to positive, detected with the driver switched on, when the line should sit at ground (GM 20 of 25 samples, MIL after two trips; Saab ME9 above 4.6 V). The valve then cannot open, the canister is not purged and fills up; the driver protects itself and the leak tests are suspended.
P0459 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 P0459
- Check engine light on
- Fuel smell when the canister is full
- EVAP readiness not set
Common causes of P0459
- Most likelyControl wire shorted to battery voltage or supply
- PossiblePurge valve coil low-resistance (shorted turns)
- PossibleConnector or harness damaged
- Less likelyEngine 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 P0459 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). |
| 59 | The exact fault in that area. |
What to do next
- Note P0459 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 P0459
What does P0459 mean?
P0459 means "EVAP System Purge Control Valve A Circuit High". 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 P0459?
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 P0459 fail an emissions test?
Yes, it can. P0459 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 P0459 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 P0459 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.