Circuit/System Description

The heated oxygen sensor (HO2S) 2 is used for catalyst monitoring. This diagnostic runs once per ignition cycle. This diagnostic consists of 2 tests, a passive test and an intrusive test. During the passive test, if the HO2S 2 voltage transitions below 290 mV and above 685 mV, the DTC will pass for this ignition cycle. If the DTC does not pass during the passive test, the intrusive test will begin. During the intrusive test, the control module will force the air-to-fuel ratio rich and/or lean. The control module then waits for a predicted response from the HO2S. If the HO2S 2 voltage transitions below 290 mV and above 685 mV, the DTC will pass for this ignition cycle.