P2232: Detecting heater interference in the bank 1 rear oxygen-sensor signal

P2232 is the bank 1 sensor 2 signal-to-heater short code. The GM strategy looks for heater coupling by examining how the sensor signal changes when the heater is turned off. The relationship to a heater transition is the central diagnostic distinction.

The observation is fast and event-based

The row compares the present signal voltage with the previous value and gives a change criterion above approximately 2.002 V. The heater-coupling observation window is less than 0.04 seconds after the relevant shutdown event. Four events are listed for the failure decision.

A steady voltage displayed well after the heater transition does not recreate that short interval. Likewise, a large signal change unrelated to heater switching is not automatically the event described by this monitor.

Readiness matters before the coupling check

The source qualifies the test with dew-point completion, heater-off state and the operating readiness of oxygen sensor 2 on bank 1. Additional enable and inhibition conditions are referenced. A cold or otherwise unready sensor cannot be judged as though the full check had completed.

Useful evidence aligns sensor voltage and heater state in time. A low-refresh display may be unable to resolve the relevant transient, so absence of a visible jump does not independently disprove the event. The code does not locate the unwanted connection within wiring or the sensor assembly. Use the actual circuit procedure to isolate it rather than replacing a sensor from a generic short-circuit description alone.

Source and scope

2025 GM 25OBDG07A Part 2 monitor tables only; model, engine and transmission applicability are not established by the unresolved application-matrix filename join. These are documented monitor criteria, not a universal repair procedure. GM PDF, physical page 512.