P0CBB: Sensor P temperature signal is unstable

P0CBB concerns hybrid/EV battery temperature sensor P circuit intermittent/erratic. In GM's 2018 HPC2/BSM table, the diagnostic evaluates accumulated changes in the signal, so it can fail without a permanently high or low temperature reading.

Read the accumulated result correctly

The calculation integrates absolute changes over ten samples. GM lists a threshold above 10 for that quantity and four failed evaluations out of five at 100-millisecond intervals. The number is not presented as a standalone overtemperature limit. Reporting is Type B, two trips.

The controller needs system voltage above 10.2 V and no active battery-interface communication fault in the designated group. Without eligible communication, a lack of a new instability result cannot be treated as proof that P's signal is sound.

What follows from the code

The source notes that an intermittent connection can create erratic readings. That supports investigating signal continuity through the applicable procedure, but it does not identify a guaranteed failed part. Preserve the time trace; a later normal value may simply show that the intermittent condition is absent at that moment.

Confirm sensor P's actual mapping rather than inferring a physical location from its letter. After repair, verify an enabled stability test with credible data and retain its outcome. Internal battery diagnosis requires qualified high-voltage service. This monitor description contains no safe probing method or pack-disassembly instructions.

Source and applicability

This explanation follows the documented GM monitor, not a verified application to every vehicle with this code. Confirm the vehicle, reporting module and calibration in current service information. GM diagnostic table, physical page 944.