what is a purge valve

A purge valve is a device used in a vehicles evaporative emission control system to remove excess fuel vapor. It traps the fuel vapors created in the fuel tank and prevents them from escaping into the air. The valve operates using a solenoid, which can sometimes malfunction and cause it to become stuck open or closed. Symptoms of a failing purge valve include poor fuel economy, engine power loss, and the check engine light turning on. To test if the purge valve is working properly, one can apply battery voltage to the purge valve terminals and see if it produces an audible click. If it does, the next step is to test if the purge valve closes properly and does not leak by connecting a hand-held vacuum pump and applying vacuum to the purge valve.