Diagnostic article Generic OBD-II
P2743: A high cooler-temperature circuit does not prove hot fluid
P2743 evaluates the cooler-out sensor’s electrical input above its window, with an explicit source-unit caveat.
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Documented application
2025 GM 25OBDG07A Part 2 documented monitor only; its application-matrix filename join is unresolved. No model, engine or universal calibration applicability is inferred.
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.
The P2743 monitor checks the cooler temperature input for an electrically high value. GM’s narrative and units describe voltage, with a threshold above 4,745 mV and 5 mV hysteresis. The criterion’s label says resistance, creating a source inconsistency that should not be silently converted into an ohmmeter specification.
Persistence and supply context
The input must meet a 500 ms confirmation interval. Monitoring is enabled with battery voltage above 8.75 V and below 18 V, outside cranking and stop-key states. P0882 or P0883 disables the check. These conditions distinguish an eligible sensor-input result from an observation during a broader controller supply problem.
“Circuit high” is not evidence that the transmission oil is excessively hot. The source is rejecting an electrical input, not reporting a validated fluid-temperature measurement.
What a verification record needs
Keep the raw signal and supply voltage together with whether the monitor actually completed. A plausible temperature value seen later does not exclude an earlier high electrical interval. Resolve the ambiguous column label through applicable service information before testing hardware. The DTC alone does not identify the cooler sensor, wiring or controller as the proven failed part.
Document scope and source
2025 GM 25OBDG07A Part 2 documented monitor only; its application-matrix filename join is unresolved. No model, engine or universal calibration applicability is inferred. These figures explain the cited controller logic, not a vehicle-specific repair instruction. Match the vehicle’s service information before applying them.
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
Transmission Fluid Temperature Sensor B Circuit High
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