Diagnostic article Generic OBD-II
P0D71: compressor CPU temperature is compared after a long off period
The GM P0D71 rationality monitor compares CPU temperature with two other temperature references after the compressor has been off for more than six hours.
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Documented application
GM 2015 15OBDG01 Hybrid Diagnostics, HCP2/VICM compressor CPU-temperature rationality monitor. Exact vehicle fitment and sensor-to-hardware mapping require the matching vehicle documentation.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P0D71 evaluates the plausibility of the electric-compressor controller's internal CPU temperature report. The cited monitor does not ask only whether the CPU temperature is high. It asks whether that report agrees with other temperatures under a carefully qualified cold-state comparison.
Two disagreements define the failure
The table requires the CPU temperature to differ from intake-air temperature by more than 10°C and from the compressor's IGBT temperature by more than 10°C. Both comparisons must fail. GM counts 35 failures out of 40 samples at a 100-millisecond interval.
The compressor must have been off for more than 21,600 seconds, or six hours. The listed temperature inputs and controller states must satisfy their validity and fault prerequisites; the coolant-to-ambient condition must also be met. An ordinary warm, operating compressor is therefore not the situation this comparison describes.
Determine which reference is trustworthy
Capture all compared temperatures and the elapsed off time. If a prerequisite sensor circuit is already faulty, resolve that evidence before using the disagreement to condemn the CPU sensor. Agreement or disagreement has meaning only when the references and qualifying state are understood.
The monitor does not provide an overheating limit or prove a cooling-system failure. It is a historical sensor-rationality example with no component-level repair sequence. Use the appropriate vehicle diagnostics, and do not open an electric compressor or its controller to investigate the temperature report without the required high-voltage and refrigerant precautions.
Source and applicability
GM 2015 15OBDG01 Hybrid Diagnostics, HCP2/VICM compressor CPU-temperature rationality monitor. Exact vehicle fitment and sensor-to-hardware mapping require the matching vehicle documentation.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
A/C Compressor Control Module Internal Temperature Sensor A Performance
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT