What is the Canister Purge Solenoid all about?
A part of the Evaporative Emission Control (EVAP) system on modern vehicles, the canister purge solenoid, more commonly known as the purge valve, helps facilitate the flow of fuel vapor from the charcoal canister to the engine for burning during the combustion process.
Controlled by the vehicle’s computer, the purge valve remains closed when the vehicle is off and opens when the engine runs according to the amount of fuel vapor detected by various sensors. Sometimes, though, problems develop when the purge valve fails to open or close properly. This can cause problems with starting the engine, having a rough running engine, as well as causing the Check Engine light to come on.
You can find the canister purge solenoid near the throttle body by the engine. In older model vehicles, you can find the purge valve on top of the charcoal canister.
Keep in mind:
- A loose gas cap can cause similar problems to a faulty purge valve. Have one of our expert mechanics check the gas cap to make sure it is working properly when diagnosing the problem. The mechanic can suggest an easy replacement if the gas cap is faulty and not just loose.
- Faulty vacuum hoses can also cause problems that mimic a stuck purge valve. Have the mechanic check your vacuum hoses to make sure they are not the cause. If they are, consider having them replaced.
How it’s done:
- The canister purge solenoid is located in the engine compartment. The electrical connector, vacuum and fuel vapor lines are disconnected.
- The defective canister purge solenoid is detached and removed.
- The new canister purge solenoid is installed and connected.
- The engine is started and checked for any vacuum and fuel vapor leaks.
- The engine is run, cleared of codes, and road tested to ensure proper purge control valve operation.
The best thing to do when you notice a problem with the vehicle idling roughly or the Check Engine light coming on is to have one of our expert mechanics run a diagnostic. After determining the cause of the problem, the mechanic will then recommend some repair options. The mechanic can also test the canister purge valve by applying voltage, which causes it to open if the part is working properly.
What common symptoms indicate you may need to replace the Canister Purge Solenoid?
- Check Engine light is on
- Engine refuses to turn over right after fueling the vehicle
- Engine idles roughly
How important is this service?
Usually a faulty canister purge solenoid won’t cause any major problems to your vehicle other than a roughly idling car. In some cases, the engine will not start right after refueling. If an emissions test is performed on your vehicle, it will not pass.