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 provides an overview of each diagnostic category.

DTC Descriptor

DTC P2440 : Secondary Air Injection System Switching Valve A Stuck Open

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Pressure Sensor 5-Volt Reference Voltage

P2432

P2431

P2431

P2430, P2431

Pressure Sensor Signal

P2432

P2432

P2433

P2430, P2431

Pressure Sensor Low Reference

--

P2433

--

-

Pump Voltage Supply

P0411

P0411

P2444

--

Pump Ground

--

P0411

--

--

Solenoid Voltage Supply

P0411

P0411

P2440

--

Solenoid Ground

--

P0411

--

--

Pump Relay Coil Voltage Supply

P0411, P0418

P0411, P0418

--

--

Pump Relay Coil Control

P0418, P2444

P0411, P0418

P0418

--

Pump Relay Switch Supply

P0411

P0411

--

--

Solenoid Relay Coil Voltage Supply

P0411, P0412

P0411, P0412

--

--

Solenoid Relay Coil Control

P0412, P2440

P0411, P0412

P0412

--

Solenoid Relay Switch Supply

P0411

P0411

--

--

Typical Scan Tool Data

AIR Pressure Sensor

Circuit

Normal Range

Short to Ground

Open

Short to Voltage

Operating Conditions: Key ON, Engine OFF

5-Volt Reference Voltage

BARO

41 kPa

41 kPa

111 kPa

Pressure Sensor Signal

BARO

42 kPa

41 kPa

150 kPa

Low Reference

BARO

BARO

145 kPa

BARO

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 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 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:

  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 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 P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0125, P0128, P0201, P0202, P0203, P0204, P0300, P0412, P0418, P0420, P0606, P1106, P1107, P1111, P1112, P1114, P1115, P1635, P1639, P2430, P2431, P2432, P2433 are not set.
    • More than 60 minutes has elapsed since the last cold start.
    • The system voltage is 9-18 volts.
    • The BARO parameter is more than 70 kPa.
    • The MAF sensor parameter is between less than 33 g/s.
    • AIR system is commanded ON.
    • Conditions are stable for more than 5 seconds.
    • 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.
    • DTC P2440 sets with in 8 seconds when the above conditions are met.

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

    •  Engine Controls Connector End Views
    •  Engine Control Module 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

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification

    • If any Secondary Air Injection System Pressure Sensor Circuit DTCs are set, perform those diagnostics first.
    • Inspect the AIR hoses/pipes between the pump and the AIR solenoid for leaks.
    • Engine running, enable the AIR pump relay and observe that the AIR Pressure Sensor parameter increases to approximately 20-25 kPa above barometric pressure (BARO).

Circuit/System Testing

  1. Disconnect the solenoid valve.
  2. Ignition ON, observe that a test lamp installed between the AIR solenoid voltage supply terminal 6 and the AIR solenoid ground circuit terminal 4 is not illuminated.
  3. If the test lamp is illuminated, test for a short to voltage on the AIR solenoid voltage supply circuit. If the circuit tests normal, test or replace the relay.
  4. Inspect the AIR pump inlet and outlet hoses/pipes for restrictions.
  5. Inspect the solenoid valve for leaks.
  6. If the solenoid valve inspects OK, replace the AIR pump.

Component Testing

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 Inlet Hose/Duct Replacement
    •  Secondary Air Injection Pump Outlet Pipe/Hose Replacement
    •  Secondary Air Injection Pump Replacement
    •  Control Module References for ECM replacement, setup, and programming

Repair Verification

Engine RUNNING, enable the AIR pump and observe that the AIR Pressure Sensor parameter increases to approximately 20-25 kPa above BARO.