Advanced Diagnostics

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 transmits a signal to the engine control module (ECM)/powertrain control module (PCM). The ECM/PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control.

If the IPB1 (pump cell current draw, bank 1) terminal voltage is out of a specified range, the ECM/PCM detects a malfunction and stores a DTC.




Monitor Execution, Sequence, Duration, DTC Type, OBD Status




Enable Conditions

Malfunction Threshold
The IPB1 terminal voltage is 2.0 V or less, or 5.6 V or more, for at least 15 seconds.

Driving Pattern
Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle for 2 minutes.

Diagnosis Details

Conditions for illuminating the MIL
When a malfunction is detected, the MIL comes on and the DTC and the freeze frame data are stored in the ECM/PCM memory.

Conditions for clearing the MIL
The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the diagnostic runs.

The MIL, the DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by disconnecting the battery.