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 | 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
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
| • | With the ignition ON and the engine OFF, observe that the MAP sensor parameter is correct for your altitude. Refer to Altitude Versus Barometric Pressure . |
| ⇒ | If the MAP sensor parameter is not correct then refer to DTC P0106 . |
| • | With the ignition ON and the engine OFF, observe that the AIR Pressure Sensor parameter is nearly identical to the MAP sensor parameter. |
| ⇒ | If the AIR Pressure Sensor and the MAP parameters are not nearly identical then proceed with Circuit/System Testing. |
| • | 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. |
| ⇒ | If the AIR Pressure Sensor parameter does not equal approximately 20-25 kPa above BARO then proceed with Circuit/System Testing. |
| • | 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. |
| ⇒ | If the AIR Pressure Sensor parameter does not equal approximately 8-10 kPa above BARO then proceed with Circuit/System Testing. |
Circuit/System Testing
- With the ignition ON and the engine OFF, observe the AIR Pressure Sensor parameter with a scan tool while manipulating all related wiring and connectors.
- With the ignition ON, the engine OFF, and the solenoid valve disconnected, measure for 5 volts between the 5-volt reference circuit and ground.
- With the ignition ON, the engine OFF, and the solenoid valve disconnected, measure for 0 volts between the low reference circuit and ground.
- With the ignition ON, the engine OFF, and the solenoid valve disconnected, inspect for an AIR Pressure Sensor parameter reading on a scan tool of 0 volts.
- With the ignition ON, the engine OFF, the solenoid valve disconnected, and a 3-amp fused jumper wire connected between the signal and 5-volt reference circuits, inspect for an AIR Pressure Sensor parameter reading on a scan tool of 5 volts.
- With the ignition ON, the engine OFF, the solenoid valve disconnected, a 300 ohm fixed resistor--an appropriate length of secondary ignition wire may be adequate--installed between the 5-volt reference circuit and the low reference circuit, and a 3-amp fused jumper connected from the signal circuit to the 5-volt reference circuit at the fixed resistor, observe an AIR pressure sensor parameter reading on a scan tool of 5 volts.
- With the ignition ON, the engine OFF, the solenoid valve disconnected, a 300 ohm fixed resistor--an appropriate length of secondary ignition wire may be adequate--installed between the 5-volt reference circuit and the low reference circuit, and a 3-amp fused jumper connected from the signal circuit to the low reference circuit at the fixed resistor, inspect for a pressure sensor parameter reading on a scan tool of 0 volts.
- If all circuits and the control module test OK then replace the solenoid valve.
| ⇒ | If manipulation does affect the AIR Pressure Sensor parameter then repair the harness or connector. |
| ⇒ | If more than 5 volts then test the 5-volt reference circuit for a short to voltage or a faulty control module. |
| ⇒ | If less than 5 volts then test the 5-volt reference circuit for high resistance, a short to ground, or a faulty control module. |
| ⇒ | If more than 0 volts then test the low reference circuit for a short to voltage or a faulty control module. |
| ⇒ | If more than 0 volts then test the signal circuit for a short to voltage or a faulty control module. |
| ⇒ | If less than 5 volts then test the signal circuit for high resistance, a short to ground, or a faulty control module. |
| ⇒ | If less than 5 volts then test the 5-volt reference circuit and the signal circuit for high resistance or a faulty control module. |
| ⇒ | If more than 0 volts then test the low reference circuit for high resistance or a faulty control module. |
Repair Instructions
| • | Control Module References for control module replacement 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.
