How To Diagnose EVAP System Leaks


1. Use a vehicle scan tool to close the EVAP vent solenoid (if kept open, this solenoid will allow smoke to naturally escape.) Alternatively, you may find a way to block the solenoid vent(s).

2. There are 3 common entryways into the EVAP system:

(A) Injecting smoke through the gas filler neck is the easiest method and requires a gas filler neck adapter. Check to see the availability of this accessory. Note : you will not be able to leak test the gas cap using this method.

(B) If your vehicle has an EVAP service port with a green cap, use the AutoLine Pro EVAP Service Kit (optional accessory) to open a gateway into the EVAP system.

(C) Locate an accessible line in the EVAP system. Disconnect it and plug up the other side.

3. Inject smoke into the system based on your selected method. If method (b) or (c), you may open the gas cap until you see smoke coming out, then close it.

4. Use a flashlight to look for smoke seeping out of leak(s) along all the lines of the EVAP system.