P2BBA: Sensor 6’s implausible temperature jump uses its own response model

P2BBA concerns erratic coolant-temperature feedback for logical sensor 6. The GM algorithm calculates an acceptable next-reading band from the preceding value and a configured response time. Its target is physically implausible change, so a reading does not have to be outside the total temperature range to fail.

The logical sensor uses a separate input calibration

In this file, coolant sensor 6 maps to the seventh configured temperature input. Its listed time constant is five seconds. The nearby sixth input has a different logical assignment and time constant, which must not be substituted merely because the code names sensor 6.

The document’s worked example uses a ten-second model and different endpoint values. That example explains the concept; its resulting bounds are not this sensor’s actual calibration.

A sequence is more informative than a snapshot

The diagnostic considers an upward change above its calculated high bound or a downward change below its calculated low bound. Relevant active high/low circuit faults are excluded, and failure is required for five seconds within a six-second window.

Retain consecutive readings, the sample context and the configured channel. A smooth-looking value after the event cannot reconstruct the failed change. The code establishes that the reported signal moved too quickly for its model, but does not prove a real coolant-temperature swing or identify an intermittent wire. Those conclusions need the applicable circuit investigation.

Source and applicability

2025 GM 25OBDG03B documented monitor only. Vehicle, engine and calibration applicability must be confirmed from the matching service information; no model fitment is inferred. These criteria explain controller logic, not a complete repair procedure. 25OBDG03B, PDF page 894. 25OBDG03B, PDF page 895. 25OBDG03B, PDF page 896.