DTC P2238
DTC P2238: Rear Air/Fuel Ratio (A/F) Sensor (Bank 1, Sensor 1) IP Circuit Low Voltage
General Description
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The rear A/F sensor (bank 1, sensor 1) transmits a signal to the powertrain control module (PCM), and the PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor (bank 1, sensor 1) signal. If the IPB1 voltage is a specified voltage when the self diagnosis function in the PCM detects an abnormal condition, the PCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type, OBD Status
| Execution | Continuous |
| Sequence | None |
| Duration | 5 seconds or more |
| DTC Type | Two drive cycles, MIL on |
| OBD Status | PASSED/FAILED/NOT COMPLETED (STILL TESTING) |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Battery voltage [BATTERY] |
9.0 V | - |
| State of the engine | Running | |
| No active DTCs set (prevents monitor from running) | P0135, P2237, P2243, P2245, P2251, P2252 | |
[ ]: HDS Parameter
Malfunction Threshold
One of these symptoms occurs:
- When the element temperature is low before the sensor becomes active:
The IPB1 voltage is 2.0 V or less for at least 5 seconds after the self diagnosis function in the PCM detects low voltage abnormal for 0.5 second.
- When the element temperature is high before the sensor becomes active:
The IPB1 voltage is 2.0 V or less for at least 5 seconds after the self diagnosis function in the PCM detects short circuit for three times and the heater is stopped for 5 seconds.
Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
- Rear A/F sensor (bank 1, sensor 1) failure
- Rear A/F sensor (bank 1, sensor 1) IPB1 line short to ground
- PCM internal circuit failure
Confirmation Procedure
Operating Condition
Start the engine. Hold the engine speed [ENGINE SPEED] at 3000 RPM without load (in P or N) until the radiator fan comes on, then let it idle for 2 minutes.
With the HDS
None.
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.
Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.