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P2440



DTC P2440

DTC DESCRIPTOR

DTC P2440
Secondary Air Injection (AIR) System Shut-Off Valve Stuck Open

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection






TYPICAL SCAN TOOL DATA

AIR Pressure Sensor:






CIRCUIT/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. The secondary AIR injection pump, provides filtered air on demand to the AIR check valve assembly. The AIR check valve assembly controls the flow of air from the AIR pump to the exhaust manifold. The AIR CONTROL relay supplies the current needed to operate the AIR solenoid that is integral to the check valve assembly. A pressure sensor, also integral to the check valve assembly, 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 signal circuit provides the control module with a voltage relative to internal AIR pressure changes.

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 control module can detect faults in the AIR pump, AIR solenoid, pressure sensor, related wiring, and the exhaust check valve. The pressure sensor can also detect leaks and restrictions in the secondary AIR system plumbing. Refer to Secondary Air Injection (AIR) System Description for further information.

CONDITIONS FOR RUNNING THE DTC
- DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0201-P0204, P0300, P0351-P0358, P0411, P0412, P0418, P0420, P0606, P0641, P0651, P1107, P2430, P2431, P2432, P2433, 2444 are not set.
- The system voltage is 9-18 volts.
- The BARO is more than 70 kPa.
- The MAF sensor is between less than 33 g/s.
- DTC P2440 runs once per trip start up when the above conditions are met and AIR pump operation is requested.
- AIR system is commanded ON.
- Conditions are stable for more than 5 seconds.

CONDITIONS FOR SETTING THE DTC
- The AIR system does not meet expected pressure conditions.
- 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.

CIRCUIT/SYSTEM VERIFICATION
1. If any other Secondary Air Injection System Pressure Sensor Circuit DTCs are set then perform those diagnostics first.
2. With the ignition ON and engine OFF, enable and disable the AIR solenoid relay and observe that the solenoid valve operates.
3. Inspect the AIR hoses/pipes between the pump and the shut-off valve for leaks.
4. With the engine running, enable the AIR pump relay and observe that the AIR Pressure Sensor parameter increases to approximately 10-20 kPa above BARO.

CIRCUIT/SYSTEM TESTING
1. With the ignition ON, the engine OFF, disconnect the check valve harness connector, connect a test lamp between the solenoid voltage supply and solenoid ground circuits terminals F and D, observe that the test lamp is not illuminated.
- If the test lamp is illuminated, test for a short to voltage on the solenoid voltage supply circuit. If the circuit test normal, replace the AIR control solenoid relay.
2. Inspect the AIR pump inlet and outlet hoses/pipes for restrictions or leaks.
- If a restriction or leak is found, remove the restriction or replace the hoses/pipes.
3. Inspect the AIR solenoid valve for any of the following conditions:
- Binding or sticking in the open position
- Leaks

COMPONENT TESTING
1. Measure the AIR solenoid for a resistance of 4.8-6.8 ohms across terminals F and D at the AIR check valve at an ambient temperature of approximately 20°C (68°F).
- If the resistance is not within range, replace the AIR check valve assembly.
2. Install a 10-amp fused jumper wire between the battery voltage supply terminal F and 12 volts. Install a jumper wire between terminal D at the solenoid valve and ground. The AIR solenoid valve should open when the jumper is connected to ground and close when the jumper is removed from ground.
- If the solenoid valve does not perform as specified, replace the check valve and assembly.

REPAIR INSTRUCTIONS

CAUTION: Allow the check valve to cool off before proceeding with the next check in order to avoid being burned. Tap on the check valve in order to remove any debris that may be inside the valve.
- Secondary Air Injection (AIR) Pump Replacement
- Secondary Air Injection (AIR) Check Valve Replacement
- Control Module References for engine control module (ECM) replacement and programming

REPAIR VERIFICATION
1. With the ignition ON and engine OFF, enable and disable the AIR solenoid relay and observe that the check valve operates.
2. Inspect the AIR hoses/pipes between the pump and the shut-off valve for leaks.
3. With the engine running, enable the AIR pump relay and observe that the AIR Pressure Sensor parameter increases to approximately 10-20 kPa above BARO.
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