P2440

DTC P2440 (WITH RPO CODE NU3)

SYSTEM DESCRIPTION
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 AIR 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:
- DTCs P0411 and P2430 run during Phase 1
- DTCs P2430 and P2440 run during Phase 2
- DTC P2444 runs during Phase 3

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

- DTC P2440-The AIR control/shut-off valve stuck open diagnostic monitors system airflow. This diagnostic test detects insufficient system pressure due to a malfunctioning AIR control solenoid valve/pressure sensor assembly or AIR valve relay, a malfunctioning AIR pump relay, or a restricted or leaking system. When the PCM detects AIR system pressure is too low DTC P2440 sets. DTC P2440 runs during Phase 2.

Phase 2
The PCM commands the AIR pump ON and the AIR control/shut-off valve Closed.
- The AIR system pressure is sufficient and DTC P2440 passes. DTC P2440 AIR Diagnostic proceeds to Phase 3.
- The AIR system pressure is not sufficient. DTC P2440 AIR Diagnostic fails, testing is stopped and DTC P2440 sets.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
- DTC P2440 Secondary Air Injection (AIR) Control/Shut-Off Valve Stuck Open

CONDITIONS FOR RUNNING THE DTC
- DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0201-P0206, P0300, P0350, P0411, P0412, P0418, P0420, P0606, P0641, P0651, P1350, P2430, P2431, P2432, P2433 are not set.
- The system voltage is between 10-18 volts.
- The engine is running.
- The start-up engine coolant temperature (ECT) is between 5-50°C (41-122°F).
- The start-up intake air temperature (IAT) is between 5-60°C (41-140°F).
- The BARO parameter is more than 60 kPa.
- The MAF sensor parameter is between 3-24 g/s.
- DTC P2440 runs once per trip start up when the above conditions are met and AIR pump operation is requested.

CONDITIONS FOR SETTING THE DTC
- The AIR system does not meet expected pressure conditions during AIR pump Phase 2 operation.
- DTC P2440 sets with in 8 seconds when the above conditions are met.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
- This DTC may set if the ignition is turned OFF and the engine is restarted within approximately 30 seconds during phase 2 of the AIR diagnostic test.
- Clear the codes and operate the vehicle within the Conditions for Running the DTC.
- If the condition is determined to be intermittent, refer to Testing for Intermittent Conditions and Poor Connections. Intermittent Conditions

TEST DESCRIPTION

Steps 1 - 6:

Steps 7 - 14:

Steps 15 - 16:

The number below refers to the step number on the diagnostic table.
4. This step tests for a short to battery positive voltage on the AIR control solenoid valve supply voltage circuit.