DTC Descriptor
DTC P2431 : Secondary Air Injection System Pressure Sensor A Circuit Range/PerformanceDiagnostic Fault Information
Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
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 | 418 2444 | P0411, P0418 | P0418 | -- |
Pump Relay Switch Supply | P0411 | P0411 | -- | -- |
Solenoid Relay Coil Voltage Supply | P0411, P0412 | P0411, P0412 | -- | -- |
Solenoid Relay Coil Control | P0411, P0412 | P0411, P0412 | P0412 | -- |
Solenoid Relay Switch Supply | P0411 | P0411 | -- | -- |
Typical Scan Tool Data
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 solenoid valve relay supplies the current needed to operate the AIR solenoid valve/pressure sensor assembly. A pressure sensor 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 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
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 control module can detect faults in the AIR pump, AIR 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 P0106, P0107, P0108, P0412, P0418, P0606, P1635, P1639, P2432, P2433 are not set. |
| • | The ignition is ON. |
| • | DTC P2431 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The control module determines that the difference between the AIR pressure sensor and the barometric pressure (BARO) sensor signals is greater than 10 kPa when the AIR pump is commanded OFF.
OR
The control module determines that the difference between the AIR pressure sensor and the BARO sensor signals is greater than 50 kPa when the AIR pump is commanded ON.
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. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Engine running, observe that the AIR Pressure Sensor parameter approximately equals BARO.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the AIR solenoid valve.
- Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal and ground.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal and ground.
- Verify the scan tool AIR Pressure Sensor parameter is less than 0.5 volts.
- Install a 3-amp fused jumper wire between the signal circuit terminal and the 5-volt reference circuit terminal. Verify the scan tool AIR Pressure Sensor parameter is greater than 4.9 volts.
- If all circuits test normal, test or replace the AIR solenoid valve.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the control module. |
| ⇒ | If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the control module. |
| ⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the control module. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the control module. |
| ⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the control module. |
Component Testing
Solenoid Valve
Apply fused battery voltage and ground to the solenoid and verify that the valve opens and closes completely as voltage is applied to and removed from the solenoid. Observe that the valve is not obstructed or leaking.
| ⇒ | If the valve operates incorrectly, leaks, or is obstructed, remove the obstruction or replace the valve. |
Repair Instructions
| • | Control Module References for control module replacement, setup, and programming |
Repair Verification
- With the key ON and the engine OFF, observe that the AIR Pressure Sensor parameter is approximately equal to BARO.
- With the engine RUNNING, enable the AIR pump with a scan tool and observe that the AIR Pressure Sensor parameter equals approximately 20-25 kPa above BARO.
- With the engine RUNNING, enable the AIR Solenoid with a scan tool and observe that the AIR Pressure Sensor parameter equals approximately 8-10 kPa above BARO.
