Diagnostic article Generic OBD-II
P0D78: driver-temperature circuit-low does not establish actual overheating
The GM P0D78 monitor evaluates an extreme converted IGBT-temperature report and has a separate recovery-enable requirement.
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Documented application
GM 2015 15OBDG01 Hybrid Diagnostics, only the cited EACCM monitor and calibration. Per-code vehicle and engine applicability has not been established; these historical thresholds are not universal service specifications.
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.
P0D78 identifies the low-circuit side of the electric-compressor output-driver temperature-sensor diagnostic. GM names the monitored value IGBT temperature. That reported temperature must be distinguished from a directly verified physical temperature of the power electronics.
An extreme report is the monitored event
The table specifies a failure when the reported driver temperature exceeds 274°C. It requires 30 failures out of 60 samples at a 50-millisecond rate, sufficient low-voltage supply and the stated Accessory or Run/Crank condition.
The printed number belongs to a circuit-range test. It is not a normal operating allowance, a refrigerant-pressure limit or a threshold that makes contact with the assembly safe. A sensor or conversion problem can create an extreme reported value without establishing the actual thermal state.
Recovery still has prerequisites
The pass comparison uses a value at or below the threshold. The source also lists a controller reset after failure before passing can be enabled. That distinction explains why a later reasonable reading and an eligible diagnostic pass are not automatically the same event.
Preserve the original driver-temperature report and related controller faults before any vehicle-specific verification. The parameter sheet does not name a failed semiconductor or authorize replacing the compressor from this code alone. Professional diagnosis needs the correct hardware information and the required high-voltage and refrigerant precautions; this explanation supplies no live electrical or internal access procedure.
Source and applicability
GM 2015 15OBDG01 Hybrid Diagnostics, only the cited EACCM monitor and calibration. Per-code vehicle and engine applicability has not been established; these historical thresholds are not universal service specifications.
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 Output Driver Temperature Sensor Circuit Low
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