P2440

DTC P2440

System Description

The DTC P2440 Secondary Air Injection (AIR) System Shut-Off Valve Stuck Open diagnostic monitors the operation of the AIR shut-off valve. The secondary AIR system helps reduce exhaust emissions. 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 shut-off valve. The AIR shut-off valve controls the flow of air from the AIR pump to the exhaust manifold. The AIR solenoid valve supplies the manifold vacuum that is used to operate the AIR shut-off valve. A pressure sensor is used to monitor the air flow from the AIR pump. By comparing the measured pressure against the expected pressure the pressure sensor can detect faults in the AIR pump, AIR shut-off valve, and the AIR solenoid valve. The pressure sensor can also detect leaks in the secondary AIR system plumbing.

Conditions for Running the DTC

* The engine is running.
* The secondary AIR solenoid valve is commanded OFF.
* DTC P2440 runs continuously once the above conditions have been met.

Conditions for Setting the DTC

The pressure sensor detects exhaust gas pulsations even when the AIR shut-off valve should be CLOSED.

Action Taken When the DTC Sets

* The PCM turns OFF the MIL on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
* The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC

* The PCM turns OFF the MIL on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
* A DTC will clear after 40 consecutive warm-up cycles have occurred without a fault.
* A DTC can be cleared by using the scan tool Clear Information function.

Test Description

The numbers below refer to the step numbers on the diagnostic table.
1. The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
3. This step tests for an always ON secondary AIR solenoid valve.
4. This step verifies the operation of the secondary AIR solenoid valve. If there is still vacuum pressure after the AIR pump is OFF, the solenoid vent passage is blocked.
5. This step tests for a shorted solenoid control circuit.
7. This step tests for a stuck OPEN secondary AIR shut-off valve.