Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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 control module 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 20-25 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 control module 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 less than 0.2 volt for at least 12.5 seconds.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

With the engine RUNNING, enable the AIR pump with a scan tool and observe that the AIR Pressure Sensor parameter equals approximately 20-25 kPa above BARO.

1. With the ignition ON and the engine OFF, observe the AIR Pressure Sensor parameter with a scan tool while manipulating all related wiring and connectors.

⇒	If manipulation does affect the AIR Pressure Sensor parameter then repair the harness or connector.

2. With the ignition ON, the engine OFF, and the solenoid valve disconnected, measure for 5 volts between the 5-volt reference circuit and ground.

⇒	If more than 5 volts then test the 5-volt reference circuit for a short to voltage or a faulty control module.

⇒	If less than 5 volts then test the 5-volt reference circuit for high resistance, a short to ground, or a faulty control module.

3. With the ignition ON, the engine OFF, and the solenoid valve disconnected, measure for 0 volts between the low reference circuit and ground.

⇒	If more than 0 volts then test the low reference circuit for a short to voltage or a faulty control module.

4. With the ignition ON, the engine OFF, and the solenoid valve disconnected, inspect for an AIR Pressure Sensor parameter reading on a scan tool of 0 volts.

⇒	If more than 0 volts then test the signal circuit for a short to voltage or a faulty control module.

5. With the ignition ON, the engine OFF, the solenoid valve disconnected, and a 3-amp fused jumper wire connected between the signal and 5-volt reference circuits, inspect for an AIR Pressure Sensor parameter reading on a scan tool of 5 volts.

⇒	If less than 5 volts then test the signal circuit for high resistance, a short to ground, or a faulty control module.

6. With the ignition ON, the engine OFF, the solenoid valve disconnected, a 300 ohm fixed resistor--an appropriate length of secondary ignition wire may be adequate--installed between the 5-volt reference circuit and the low reference circuit, and a 3-amp fused jumper connected from the signal circuit to the 5-volt reference circuit at the fixed resistor, observe an AIR pressure sensor parameter reading on a scan tool of 5 volts.

⇒	If less than 5 volts then test the 5-volt reference circuit and the signal circuit for high resistance or a faulty control module.

7. With the ignition ON, the engine OFF, the solenoid valve disconnected, a 300 ohm fixed resistor--an appropriate length of secondary ignition wire may be adequate--installed between the 5-volt reference circuit and the low reference circuit, and a 3-amp fused jumper connected from the signal circuit to the low reference circuit at the fixed resistor, inspect for a pressure sensor parameter reading on a scan tool of 0 volts.

⇒	If more than 0 volts then test the low reference circuit for high resistance or a faulty control module.

8. If all circuits and the control module test OK then replace the solenoid valve.

With the engine RUNNING, enable the AIR pump with a scan tool and observe that the AIR Pressure Sensor parameter equals approximately 20-25 kPa above BARO.