A canister purge valve is part of the Evaporative Emission Control (EVAP) system of a vehicle. The EVAP system captures fuel vapors that evaporate from the fuel tank and reroutes them to be burned in the engine rather than be allowed to escape into the atmosphere. Fuel vapors that vent outside result not only in a loss of fuel, but also in emissions that are harmful to the environment and people.
Also known as a purge solenoid, the canister purge valve allows the fuel tank to be vented so that pressure does not build up inside. At the same time, it prevents those vapors from escaping. Vapors that are collected are stored in a special vapor canister where they are absorbed by activated carbon (charcoal) and stored there until the engine control module (ECM) signals the canister purge valve to open. Once the valve opens, the fumes stored in the canister are drawn out by the engine and burned as part of the combustion process.
A check engine light is a common sign that a canister purge valve has failed. A diagnostic scan of the vehicle will reveal a trouble code related to pressure in the EVAP system. Besides the check engine light and related trouble code, other possible symptoms include:
To replace the canister purge valve, a technician will take the following general steps:
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