Diagnosis of Canister Purge Valve (CPV) (under driving conditions)

Step 1 Check of purge vapor factor (for rich or lean mixture):

Flow through the purge valve is inferred as soon as the lambda controller compensates for a rich or a lean shift. After rich procedure the diagnosis is completed and the evaporative purge system resumes normal operation.

Step 2 Test of canister pressure (for a stoichiometric or lean mixture):

In case of a stoichiometric or lean mixture an additional check is performed by opening the purge valve during Evap leak detection. When the purge valve opens, the pressure in the tank system drops proportional to the DM-TL pump current. If A pump current > threshold, the purge valve is considered operational.