1.4.1.1 Monitoring Function

The diagnosis is used for the functional test of the EVAP Canister Purge Solenoid. This test consists of two checks.

The first EVAP Canister Purge Solenoid test is based on the amount in the Active Charcoal Filter (ACF). The "canister load diagnosis" is continuously calculated during the tank purge.

When the amount calculated is above the threshold, the canister load is diagnosed as being in working order.

When the amount calculated is below the threshold, the next step is performed.

The EVAP Canister Purge Solenoid is evaluated based on the deviation in the manifold pressure during this next step, which takes place while the motor is running in idle speed. The EVAP Canister Purge Solenoid is opened for a short time, during which the manifold pressure is monitored. Additionally, the deviation of lambda-controller (rich mixture) is monitored.

After this test has been enabled, it is executed in each idle speed phase, as long as the monitoring conditions are met, and is repeated as long as a result is reached. This test is not bound to one idle speed phase, but can be distributed to several idle speed phases.

When the EVAP Canister Purge Solenoid is diagnosed as not being in correct working order three times, the error is set.