Air Injection: Testing and Inspection

AIR SYSTEM SELF TESTING
The PCM monitors the AIR system in two stages (Passive and Active). The PCM initiates a two part Passive Test (stage 1) once each ignition cycle. Part one monitors the HO2S response when the PCM commands the air pump ON. If the HO2S remains proportionally lean (low HO2S signal) for a minimum of 5 seconds, part one passes and part two of the passive test is initiated. The second part of the passive test monitors the transition from open loop to closed loop fueling. When air injection to the exhaust is commanded OFF, the PCM monitors the HO2S response. If the HO2S signal switches from a lean to rich condition for a specific amount of time, part two passes. If part one and part two pass, further monitoring of the AIR system is discontinued. If any portion of the Passive Test fails, the PCM initiates the Active Test (stage 2). To run the Active Test, the AIR pump is commanded ON during warmed-up, closed loop operation. The PCM monitors the HO2S and long and short term fuel trim value response to air injection. If the HO2S signal remains proportionally lean (low HO2S signal) and the long and short term fuel trim values increase for a specific amount of time, the active test passes. If the HO2S and long and short term fuel trim values do not respond to air injection, the active test fails. If the PCM detects a consecutive number of active test failures, the appropriate DTC(s) will set. If a successful test occurs during the active test stage, a pass indication results and the test will not run until the next ignition cycle. Conditions for setting the AIR system fault:

^ No active VSS, TP sensor, EVAP System, HO2S sensor, Misfire, IAT sensor, MAP sensor; IAC, Fuel Trim, Fuel Injector circuit, EGR Pintle, ECT sensor, CKP sensor or MAF sensor PTC(s) are set.
^ ECT sensor signal indicates temperatures between 75°C - 110°C (167°F - 230°F).
^ Engine run time greater than 3 seconds.
^ System voltage is greater than 9 volts.
^ Engine load less than 36%.
^ MAF less than 35 gm/s.
^ HO2S1 signal voltage remains greater than 300 mV (0.3 volt) for 3 occurrences.

SCAN TOOL TESTING
The Powertrain Control Module monitors the - Secondary Air Injection Reaction (AIR) System. A system malfunction will set DTC P0410. An Output Driver Module (0DM A output 2) failure will set DTC P1642. The appropriate DTC chart should be used in diagnosing a AIR DTC. Refer to the proper DTC to diagnose the AIR failure. Testing and Inspection

RESULTS OF INCORRECT AIR SYSTEM OPERATION
If, during open loop fuel control, air injection isn't present in the exhaust stream, high first and second hydrocarbon emissions result.
Continuous air injection to the exhaust stream will result in the following condition(s):

^ DTC P0131 and/or P0410 will set.
^ Open loop fuel control will be in effect.
^ Backfiring in the exhaust/catalyst system may occur.
^ Catalyst damage may occur.

No air injection to the exhaust stream will result in the following condition(s):

^ DTC P0410 will set.
^ High Hydrocarbon and Carbon monoxide emissions will occur during open loop fuel control.