P2237: Wide-range oxygen sensor pump-current circuit is diagnosed open

P2237 is an open pump-current signal-circuit diagnosis for bank 1 sensor 1 in the reviewed GM wide-range oxygen-sensor system. The ECM receives diagnostic information from the sensor interface integrated circuit, rather than deciding solely from an ordinary oxygen-voltage trace.

Hardware variants change the electrical signature

The ATIC142 interface can flag an open pump-current pin or a combination of pump-cell voltage above 1.2 V and reference-cell voltage below 1.2 V. Its internal qualification includes passive and active stages totaling 2.5 seconds.

The same table also describes a CJ136 interface with sensor-dependent resistance criteria and a different internal qualification interval. Those alternatives should not be combined into a single universal bench test. Identify the actual interface and sensor type before interpreting detailed electrical limits.

The ECM has its own decision window

After an interface fault indication, the ECM counts 20 failures out of 24 at 25-millisecond intervals. Monitoring requires valid measurement status, a ready controller, engine run or auto-stop status, completed heater warm-up and more than 20 seconds of circuit-diagnostic delay. Listed heater and bank-level faults must be absent.

A cold-start observation before these conditions are met does not demonstrate a passed pump-current test. Likewise, a lean-looking exhaust signal alone does not establish an open circuit.

Verification should confirm valid interface operation and completion of the enabled circuit monitor after the identified fault is addressed. The source specifies Type B, two trips, without prescribing a particular sensor replacement.

Source and applicability

The documented system and calibration must be confirmed for the vehicle before using these limits. GM diagnostic table, PDF page 619. GM diagnostic table, PDF page 620.