P0C45: Inlet-temperature circuit high can display below −40°C

P0C45 is the high-circuit fault for the battery-coolant inlet-temperature signal in this GM monitor. The threshold shown is an inlet temperature below −40°C with ADC count above 3823. The electrical high label is therefore not a statement that the coolant itself is hot.

Interpret the converted value cautiously

A very cold display can result from the sensing path represented by the ADC count. This code alone does not establish actual coolant temperature. Preserve the original electrical and temperature reports for a technician using the appropriate circuit procedure.

Qualification requires 1.75 seconds of failure within a 2.5-second window, with 250-millisecond evaluations. The pass row requires at least −40°C and ADC no greater than 3823 for 2.5 seconds. A momentary return to an acceptable reading does not meet that entire recovery definition.

Confirm valid operating support

The diagnostic requires enabled operating-state communication and sensing-controller voltage of at least 9 volts. Those conditions should be part of the record when comparing the original event with a later assessment.

The source's strategy sentence says the sensor goes above a threshold, whereas its converted-temperature limit is cold; this wording discrepancy remains explicit. The document supplies no universal inlet-sensor location or replacement instruction. Physical inspection of the battery cooling and high-voltage systems belongs to qualified personnel following the exact vehicle service information.

Source and applicability

15OBDG01 Hybrid Diagnostics, cited controller and monitor only. Historical calibration limits are not universal specifications; per-code vehicle, engine and hardware applicability must be verified.

GM source, physical page 641.