EVAP Purge Valve
What it is
The purge valve (purge solenoid) is part of the evaporative emissions (EVAP) system that captures fuel vapours from the tank. It is a small, inexpensive electrically controlled valve.
What it does
It opens to let stored fuel vapour from the charcoal canister be drawn into the engine and burned, instead of escaping to the atmosphere. Stuck open it causes a rough idle and stalling; stuck closed or leaking it sets EVAP codes like P0441/P0455.
Symptoms of failure
- EVAP codes such as P0440, P0443, P0444, P0455 or P0456
- Rough idle or stalling (stuck open)
- Hard starting just after refuelling
- Check engine light with no drivability change
- Faint fuel smell
Common fault codes
Which vehicles need it
All modern petrol cars. A cheap, common fix for EVAP codes alongside the gas cap.
Replacement cost
| DIY (part only) | $15–$60 |
|---|---|
| At a shop (parts + labor) | $100–$250 |
| Replacement interval | No set interval — replace on failure. |
| DIY difficulty | Easy (DIY) — usually clips on with one connector and one hose |
| Recommended brands | Standard Motor Products, Dorman, Delphi, OEM |
Where to buy the part
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Frequently asked questions
Can a purge valve cause a rough idle?
Yes. A purge valve stuck open creates an unmetered vacuum leak that makes the engine idle roughly or stall, especially right after starting. It is a common, cheap cause to check.
Is a purge valve the same as the gas cap?
No, but both are part of the EVAP system and both are common, cheap causes of EVAP leak codes. On a small-leak code (P0455/P0456) check the gas cap first, then the purge and vent valves.