OBD II Readiness Monitors

OBD Drive Cycles

Secondary AIR System Monitor

When vehicles are equipped, the secondary AIR system monitor allows the PCM to ensure that extra air is being delivered to the exhaust system during cold engine operating conditions. This extra air helps heat the catalytic converter quickly when the engine is first started. The PCM uses the signal from the upstream oxygen sensor to detect the presence of extra air in the exhaust manifold supplied by the AIR system.

The monitor usually runs on the start up of a cold engine, conditions permitting. If the monitor does not successfully execute on cold start up, the PCM can force the monitor to run during normal idling conditions. As with most other monitored OBD II systems all AIR electrical components are checked for electrical and rationality faults during continuous monitoring. In order for the PCM to enable the secondary AIR system monitor the check engine light has to be commanded off, continuous monitors and the oxygen sensor monitor must have been successfully completed.

The PCM will successfully complete the secondary AIR system monitor if the proper voltage signal is detected from the upstream oxygen sensor. If an incorrect oxygen sensor signal is detected the PCM will set a pending code. The PCM will command the check engine light to illuminate and store a DTC if the fault occurs during 2 drive cycles.