1.4.1.1 Diagnosis of Canister Purge Valve under Driving Conditions

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

Flow through the CPV is inferred as soon as the lambda controller compensates for a rich or for a lean shift. The diagnosis is complete after rich procedure has occurred. The EVAP purge system then resumes normal operation.

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

For stoichiometric or for lean mixtures, an additional check is executed by opening the CPV during the EVAP leak detection. When the CPV opens, the pressure in the tank system drops proportionally to the DMTL pump current. When the Δpump current exceeds the threshold, the CPV is diagnosed as being operational.