GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provide an overview of each diagnostic category.

DTC Descriptor

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

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Pressure Sensor 5-Volt Reference Voltage

P0335, P0651, P2135, P2432

P2432

P2431, P0651

P2430, P2431

Pressure Sensor Signal

P2432

P2432

P2433

P2430, P2431

Pressure Sensor Low Reference

--

P2433

--

P0411, P2431

Pump Supply

P0411

P0411

2444

--

Pump Ground

--

P0411

--

--

Solenoid Supply

P0411

P0411

P2440

--

Solenoid Ground

--

P0411

--

--

Pump Relay Coil Supply

P0102, P0412, P0418,

P0418

P0690

--

Pump Relay Control

P0418

P0418

P0411, P0418, P0690, P2431

--

Pump Relay Switch Supply

P0411

P0411

--

--

Solenoid Relay Coil Supply

P0412

P0411, P0412

P0690

--

Solenoid Relay Control

P0412

P0411, P0412

P0411, P0412, P0690

--

Solenoid Relay Switch Supply

P0411

P0411

--

--

Typical Scan Tool Data

AIR Pressure Sensor

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Key ON, Engine OFF

Parameter Normal Range: BARO

5-Volt Reference Voltage

41 kPa

41 kPa

111 kPa

Pressure Sensor Signal

41 kPa

41 kPa

145 kPa

Low Reference

BARO

145 kPa

--

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. 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 solenoid 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:

    • 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 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.

Conditions for Running the DTC

    • DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0201-P0208, P0300, P0351-P0358, P0411, P0412, P0418, P0420, P0606, P0641, P0651, P2430, P2431, P2432, P2433, 2444 are not set.
    • The system voltage is 11-18 volts.
    • The start-up engine coolant temperature (ECT) is between 5-80°C (41-176°F).
    • The start-up intake air temperature (IAT) is greater than 5°C (41°F).
    • The BARO is greater than 70 kPa.
    • The MAF sensor is 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 greater than 5 seconds.

Conditions for Setting the DTC

    • The ECM determines that the actual AIR system pressure is 3 kPa less than the predicted AIR system pressure.
    • DTC P2440 sets during phase 2 when the above condition is met for greater than 2 seconds.

Action Taken When the DTC Sets

DTC P2440 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P2440 is a Type B DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Verify that DTCs P0412, P0418, P0641, P0651, P2430, P2431, P2432, P2433 or P2444 are not set.
  2. If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.
  3. Ignition ON, enable and disable the AIR solenoid relay and observe that the solenoid valve operates.
  4. Inspect the AIR hoses/pipes between the pump and the shut-off valve for leaks.
  5. Engine running, enable the AIR pump relay and observe that the AIR Pressure Sensor parameter increases to approximately 15-22 kPa above BARO.
  6. 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.

Circuit/System Testing

  1. Disconnect the harness connector at the AIR solenoid valve.
  2. Ignition ON, connect a test lamp between the AIR solenoid voltage supply terminal 6 and the solenoid ground circuit terminal 4, the test lamp should not illuminate.
  3. If the test lamp illuminates, test the AIR solenoid supply voltage circuit for a short to voltage. If the circuit tests normal, test or replace the AIR solenoid relay.
  4. Inspect the AIR pump inlet and outlet hoses/pipes for leaks or restrictions.
  5. Inspect the AIR solenoid valve for leaks.
  6. If the solenoid valve tests normal, replace the AIR pump.

Component Testing

AIR Solenoid Static Test

Measure the AIR solenoid for a resistance of 4.8-6.8 ohms across the B+ terminal 6 and the ground terminal 4 at the AIR solenoid valve at an ambient temperature of approximately 20°C (68°F).

If the resistance is not within range, replace the AIR solenoid valve assembly.

AIR Solenoid Test

Install a 10A fused jumper wire between the battery voltage supply terminal and 12 volts. Install a jumper wire between ground terminal 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 AIR solenoid valve and assembly.

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.

Repair Instructions

    •  Secondary Air Injection Check Valve Replacement
    •  Secondary Air Injection Pump Replacement
    •  Control Module References for ECM replacement and programming

Repair Verification

  1. Ignition ON, enable and disable the AIR solenoid relay and observe that the AIR solenoid valve operates.
  2. Engine running, enable the AIR pump relay and observe that the AIR Pressure Sensor parameter increases to approximately 15-22 kPa above BARO.