P058C: two internal battery temperatures disagree

P058C is a battery-monitor temperature plausibility fault. The detailed BCM source compares raw ASIC and NTC temperatures supplied by the intelligent battery sensor. The absolute difference must exceed 10 degrees Celsius for the documented failure decision.

Difference is the key measurement

Two temperatures can each look possible yet disagree enough to fail this monitor. Conversely, a very high temperature alone is not the comparison described by P058C. The BCM example excludes the separate temperature out-of-range faults, including P058E and P058F, before evaluating this plausibility check.

The continuous BCM evaluation requires eight seconds of failure in a ten-second window. The ECM example expresses the decision as eight failed samples out of ten. These descriptions should stay attached to their respective controller implementations.

Why wakeup history matters

The IBS stores up to twenty-four sets of temperatures at thirty-minute intervals while LIN is off. Those stored values support a historical diagnostic immediately after wakeup; the continuous diagnostic then evaluates live information repeatedly. Presently matching temperatures do not necessarily refute a historical disagreement.

To assess the code, identify whether the available result comes from stored sleep-time samples or the current comparison, and inspect both raw temperatures rather than only a combined battery-temperature PID. Valid communication, ambient conditions and supply voltage also enable the test. A successful repair verification needs the relevant comparison to pass, not simply one temperature to appear reasonable.

Source and applicability

Documented monitors in gm-2025-03a, gm-2025-04b, model year 2025. These are module/calibration examples; vehicle, engine and transmission applicability must be confirmed independently. GM 2025-03a, page 349. GM 2025-04b, page 70.