Secondary Air System Monitoring

Secondary air monitoring structure





Tables of OBD Requirements for Secondary air System Monitoring

GENERAL DESCRIPTION

At cold start the secondary air pump and valve are switched on for their normal operating function. The secondary air delivered into the exhaust gas is causing a lean mixture indicated by the output voltage of the oxygen sensor.
Any time the oxygen sensor indicates a lean mixture within the maximum time for monitoring a counter is incremented by "one" up to a predetermined value.
This fixed limit corresponds to the minimum amount of secondary air (low-flow-limit-check).

CONDITIONS FOR ENABLING DIAGNOSIS

The diagnosis is performed only if the secondary air pump is switched on.

The sampling of measured values (rate = 20 ms) will be started if the following conditions are met for at least 0.7 seconds:
- oxygen sensor is heated up (stabilized conditions)
- cold start enrichment activated
- coolant temperature > - 10°C and < 70.5°c





- criteria for high altitude driving conditions:

If the altitude criteria are fulfilled continuously the diagnosis function is still active even at elevations above 3000 m (9842 ft).