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 engine control module (ECM) 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 ECM 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.

DTCs P0412 and P0418 are Type B DTCs.

DTCs P0412 and P0418 are Type B DTCs.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Verify with a scan tool that the ECM is not commanding the affected relay activation.
2. Ignition ON, command the affected relay ON and OFF with a scan tool. Feel or listen to verify that the affected relay turns ON and OFF with each command.
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, disconnect the affected relay.
2. Verify that a test lamp does not illuminate between B+ and the affected relay control circuit terminal.

⇒	If the test lamp does illuminate, test the control circuit for a short to ground.

3. Remove the test lamp.
4. Command the affected relay ON with a scan tool. Verify the scan tool Relay Control Ckt. Short Volts Test Status Parameter is OK.

⇒	If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

5. Install an appropriately fused jumper wire between the control circuit terminal and B+. Command the affected relay ON with a scan tool. Verify the scan tool Relay Control Ckt Short Volts Test Status Parameter is Fault.

⇒	If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

6. Remove the fused jumper wire.
7. Connect an appropriately fused jumper between the positive voltage terminal at the battery and the affected load voltage supply circuit terminal 87 at the affected relay connector and verify affected load activation.

⇒	If the affected load does not activate, test the affected load voltage supply circuit terminal 87 for a short to ground or an open/high resistance. If the circuit tests normal, replace the affected load.

8. Ignition ON, connect an appropriately fused jumper between the relay switch voltage supply circuit terminal 30 and the affected load voltage supply circuit terminal 87 at the affected relay connector and verify affected load activation.

⇒	If the affected load does not activate, test the affected relay switch voltage supply circuit terminal 30 for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.

9. Ignition ON, verify that a test lamp illuminates between the affected relay coil voltage supply circuit terminal and ground.

⇒	If the test lamp does not illuminate, test the affected relay coil voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.

10. If all circuits and the ECM test normal, test or replace the affected relay.

Relay Test

1. Test between the normally-closed switch terminals, if any, for 0 ohms.
2. Test between the normally-open switch terminals for infinite ohms.
3. Test between each switch terminal and either coil terminal for infinite ohms.
4. Connect the relay coil terminals to ground and fused power to energize the relay.
5. Test between each switch terminal and each coil terminal for 0 volts.
6. Test between the normally-closed switch terminals, if any, for infinite ohms.
7. Test between the normally-open switch terminals for 0 ohms.

Control Module References for control module replacement, set up, and programming

Ignition ON, command the affected relay ON and OFF with a scan tool. Feel or listen to verify that the relay turns ON and OFF with each command.