Description And Operation: Notes

DESCRIPTION 

The Catalyst Monitoring system consists of the following components:

OPERATION 

The State of Change (SOC)  catalyst monitor uses the signals from both the Upstream and Downstream Oxygen (O2) Sensors to detect aging of the catalyst. The Upstream O2 Sensor slow response monitor runs simultaneously to determine if the sensor signal is plausible. A pass/fail determination is made on the O2 Sensor slow response diagnostic before a catalyst determination is made to prevent a false fail of the catalyst monitor. These monitors are intended to determine when the O2 Sensor and catalyst systems have deteriorated to the point that tailpipe emissions exceed the appropriate malfunction limit.