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Diagnostic Aids

WARNING: This page is about a different car, the 2003 Cadillac Seville and 2003 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.

Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help to diagnose the condition. The information may help to determine how often the condition that set the DTC occurs.

  1. Inspect for the following conditions:
    • A low AIR system airflow may cause this DTC to set.
    • Any excessive exhaust system back-pressure.
    • Any moisture, water, or debris ingestion into the AIR pump.
    • Any restrictions in the AIR pump inlet, duct, or filter.
  2. An intermittent may be caused by any of the following conditions:
    • Any pinched hoses or vacuum lines.
    • Any kinked pipes/hoses or vacuum lines.
    • Any split pipes/hoses or vacuum lines.
    • Any heat damaged pipes.
    • Any deteriorated hoses or vacuum lines.
  3. Any reversed inlet and outlet hoses at the AIR pump may cause a reduced airflow. This condition may cause this DTC to set. The AIR pump inlet and outlet ports should be clearly identified on the pump.
  4. An AIR solenoid stuck open or leaking vacuum internally may hold the shut-off valves open, an audible exhaust popping noise may be heard through the air pump inlet hose. This condition may not set a code and may cause the fuel trim parameters to indicate a high percentage value at an idle.
  5. The AIR solenoid vents the vacuum from the shut-off valves when the system is inactive. Verify proper connections of vacuum hoses, reversed connections at the AIR solenoid may cause the AIR shut-off valves to be held open.
  6. When commanding the AIR System on with a scan tool the PCM will activate the AIR pump and the AIR solenoid. The fuel control system will then enter Open Loop status. This action will allow fresh air to enter the exhaust stream and cause the HO2S mV parameter to drop to near zero mV. This would indicate a properly operating AIR system.
  7. However if the AIR pump does not operate or there is no airflow from the pump entering the exhaust stream due to a leak in the system, the HO2S parameter may still drop below 100 mV. This is due to the fresh air being drawn into the exhaust stream from the opening of the shut-off valves. The HO2S will respond with a drop in mv readings as a result of this air leaning out the exhaust. The voltages may decrease to below 100 mV but not approach zero mV.
  8. If the condition is intermittent, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
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