P0410

Diagnostic Chart:

Electrical:

CIRCUIT DESCRIPTION

The purpose of the Secondary Air Injection (AIR) system is to reduce Hydrocarbon (HC), the Carbon Monoxide (CO), and the Oxides of Nitrogen (NOx) exhaust emissions by causing any combustible gases in the exhaust to re-burn. This also causes the catalytic converters and the heated oxygen sensors to reach the normal operating temperatures more quickly, thus Closed Loop operation occurs earlier.

When the engine is started, the ECM commands the AIR pump relay and the AIR Cutoff Valve Vacuum Control solenoid on, injecting clean air into the engine exhaust ports. The ECM switches the AIR system off when the oxygen sensors become active. The AIR Cutoff Valve prevents air from being drawn into the system when the AIR pump is off. The vacuum to the valve is controlled by the AIR Cutoff Valve Vacuum Control solenoid. A check valve close to the engine prevents hot exhaust gases from backing up into the AIR system.

The ECM uses the Short Term Fuel Trim in order to diagnose the AIR system. When the AIR system is enabled, the ECM monitors the Short Term Fuel Trim. If the Short Term Fuel Trim goes below a threshold, the ECM interprets this as an indication that the AIR system is operational. When the AIR pump is disabled, the Short Term Fuel Trim should return to normal.

CONDITIONS FOR RUNNING THE DTC

^ P0100, P0110, P0115, P0116, P0120, P0133, P0153, P0171, P0172, P0174, P0175, P0300 thru P0306, P0560, P0440, P0441, or P0443 not set.

^ The Closed Loop is enabled

^ The EVAP purge disabled.

^ The IAT is greater than 5.3°C (41.5°F).

^ The ECT is greater than 18.8°C (65.8°F).

^ The engine is at idle.

^ Vehicle speed=0 miles/h.

^ The short term fuel trim is above the minimum limit of approximately -25%.

CONDITIONS FOR SETTING THE DTC

The Short term fuel trim remains below a predetermined value for at least 20 seconds.

ACTION TAKEN WHEN THE DTC SETS

The ECM illuminates the Malfunction Indicator Lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The ECM turns off the MIL after three consecutive drive trips that the diagnostic runs and does not fail.

^ A History DTC clears after forty consecutive warm-up cycles if no failures report by this diagnostic or any other emission related diagnostic.

^ The ECM battery voltage is interrupted.

^ The scan tool clears the MIL/DTC.

DIAGNOSTIC AIDS

^ Use the Connector Test Adapter Kit J 35616-A for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

^ Check the AIR system for an intermittent problem. Check for the following conditions:

- An intermittent short to B+ on the pump feed circuit.

- Sticking relay contacts

- A sticking AIR cutoff valve

Refer to Symptoms / Intermittents. Testing and Inspection

TEST DESCRIPTION

The number(s) below refer to the step numbers on the diagnostic table.

2. At start up, the ECM may be commanding the AIR pump on if the conditions are appropriate. Let the engine run long enough in order to enter a Closed Loop operation.

15. Inspect the check valve. Check the hoses after the check valve for evidence of heat damage. A heat damaged hose indicates that the check valve is stuck open, allowing exhaust gas back into the AIR system, and allowing the outside air to be drawn into the exhaust stream.