DTC Advanced Diagnostics: P2237 (3.5L Engine)
DTC P2237: Rear Air/Fuel Ratio (A/F) Sensor (Bank 1, Sensor 1) IP Circuit High 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 terminal voltage is out of a specified range when the rear A/F sensor (bank 1, sensor 1) pump cell voltage is excessively high, the PCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous |
| Sequence | None |
| Duration | 15 seconds or more |
| DTC Type | Two drive cycles, MIL on |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| 12 volt battery voltage [Battery] | 9.0 V | - |
| State of the engine | Running | |
[ ]: HDS Parameter
Malfunction Threshold
The IPB1 terminal voltage is in between 1.94 - 2.06 V for at least 15 seconds.
Possible Cause
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 open
- PCM internal circuit failure
Confirmation Procedure
Operating Condition
Start the engine. Hold the engine speed [Engine Speed] at 3, 000 RPM without load (in P or N) until the radiator fan comes on, then let it idle for 2 minutes.
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, the freeze data, and the on-board snapshot 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, the freeze data, and the on-board snapshot can be cleared with the scan tool clear command.