The secondary air injection (AIR) system aids in the reduction of hydrocarbon emissions during a cold start. The system forces fresh filtered air into the exhaust stream in order to accelerate the catalyst operation. An electric air pump, the secondary AIR injection pump, provides filtered air on demand to the AIR control solenoid valve/pressure sensor assembly. The AIR control solenoid valve/pressure sensor assembly controls the flow of air from the AIR pump to the exhaust manifold. The AIR valve relay supplies the current needed to operate the AIR control solenoid valve/pressure sensor assembly. A pressure sensor is used to monitor the air flow from the AIR pump. The powertrain control module (PCM) supplies the internal pressure sensor with a 5-volt reference, an electrical ground, and a signal circuit.

The AIR diagnostic uses 3 phases to test the AIR system:

1. DTCs P0411 and P2430 run during Phase 1
2. DTCs P2430 and P2440 run during Phase 2
3. DTC P2444 runs during Phase 3

During phase 1, both the AIR pump and the solenoid valve are activated. Normal secondary air function occurs. Expected system pressure is 8-10 kPa above BARO.

During phase 2, only the AIR pump is activated. The solenoid valve is closed. Pressure sensor performance and solenoid valve deactivation are tested. Expected system pressure is 15-20 kPa above BARO.

During phase 3, neither the AIR pump nor the solenoid valve is activated. AIR pump deactivation is tested. Expected system pressure equals BARO.

In all 3 phases, testing is accomplished by comparing the measured pressure against the expected pressure. The PCM can detect faults in the AIR pump, AIR control solenoid valve/pressure sensor assembly, and the exhaust check valve. The pressure sensor can also detect leaks and restrictions in the secondary AIR system plumbing.

The pressure sensor signal is more than 4.8 volts for at least 12.5 seconds.

DTC P2433 is a Type B DTC.

DTC P2433 is a Type B DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

1. Ignition ON, verify that the AIR pump is not activated.
2. Ignition ON, observe that the AIR Pressure Sensor parameter approximately equals the BARO parameter.

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If not equal, verify that the BARO parameter is correct for your altitude. Refer to Altitude Versus Barometric Pressure . If the reading is not correct for your altitude, diagnose the MAP sensor. Refer to Manifold Absolute Pressure Sensor Diagnosis . If the BARO parameter is correct for your altitude, proceed with Circuit/System Testing.

3. Engine running, enable the AIR solenoid with a scan tool and observe that the AIR Pressure Sensor parameter equals approximately 8-10 kPa above BARO.

⇒	If less than the specified range, verify that the AIR pump is activating. If AIR pump activation is normal, proceed with Circuit/System Testing.

Important: The Circuit/System Verification must be performed first or misdiagnosis may result.

1. Ignition OFF, disconnect the harness connector at the AIR solenoid valve.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the PCM.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal and ground.

⇒	If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PCM.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the PCM.

4. Verify the scan tool AIR Pressure Sensor parameter is less than 0.5 volts.

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the PCM.

5. Install a 3A fused jumper wire between the signal circuit terminal and the 5-volt reference circuit terminal. Verify the scan tool AIR Pressure Sensor parameter is greater than 4.9 volts.

⇒	If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the PCM.

6. Ignition OFF, connect all electrical connectors.
7. Ignition ON, engine OFF, observe the AIR Pressure Sensor parameter.

⇒	If the AIR Pressure Sensor parameter does not equal the BARO parameter, replace the AIR solenoid valve.

8. Engine running, enable the AIR solenoid valve with a scan tool and observe that the AIR Pressure Sensor parameter equals approximately 8-10 kPa above BARO.

⇒	If not within the specified range, continue with this procedure.

9. Remove the AIR inlet hose from the AIR pump.
10. Engine running, enable the AIR solenoid valve with a scan tool and observe that the AIR Pressure Sensor parameter increases to 8-10 kPa above BARO.

⇒	If within the specified range, the AIR pump inlet hoses/pipes are restricted. Remove the restriction or replace the hose/pipe.

⇒	If not within the specified range, continue with this procedure.

11. Disconnect the hose from the AIR pump outlet.
12. Disconnect the hose quick-connect from the AIR solenoid valve inlet.
13. Install a length of standard 1 inch I.D. (25.4 mm) hose from the AIR pump outlet to the AIR solenoid valve inlet.
14. Engine running, enable the AIR solenoid valve with a scan tool and observe that the AIR Pressure Sensor parameter increases to 8-10 kPa above BARO.

⇒	If within the specified range, the AIR pump outlet hoses/pipes are restricted or leaking. Remove the restriction or replace the hose/pipe.

⇒	If less than the specified range, replace the AIR pump.

⇒	If more than the specified range, continue with this procedure.

15. Remove the AIR solenoid valve.
16. Leave the standard hose and harness connector connected.
17. Engine running, enable the AIR solenoid valve with a scan tool and observe that the AIR Pressure Sensor parameter increases to approximately 7 kPa above BARO.

⇒	If more than the specified range, replace the AIR solenoid valve.

⇒	If approximately the specified value, the exhaust system is restricted. Remove the restriction or replace the appropriate component.

Solenoid Valve

1. Apply appropriately fused battery voltage and ground to the solenoid terminals and verify that the valve opens and closes completely as voltage is applied to and removed from the solenoid terminals . Observe that the valve is not obstructed or leaking.

⇒	If the valve operates incorrectly, leaks, or is obstructed, remove the obstruction or replace the valve.

With the ignition ON and the engine OFF, observe that the AIR pressure sensor parameter is nearly identical to the MAP sensor parameter.