Diagnostic article Generic OBD-II
P0873: system-pressure sensor high voltage with conflicting enables
P0873 monitors a high electrical signal from the transmission system-pressure sensor in the supplied table.
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Documented application
2025 GM 25OBDG07A Part2 diagnostic monitor documentation; the application-matrix filename mismatch is unresolved, so no model or engine 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.
P0873 monitors a high electrical signal from the transmission system-pressure sensor in the supplied table. The generic pressure-sensor C label must be matched to that system-pressure channel for the actual vehicle.
Supported high-signal details
The row gives a threshold above 4,530 millivolts, 30 millivolts of hysteresis, and at least 150 milliseconds of confirmation. It also lists battery voltage between 8.75 and 18 volts, excludes cranking and Stop key status, and names P0882, P0883, P0652, and P0653 as disabling faults.
The VREF2 enable entries are contradictory: one requires supply above 5.5 volts and another below 4.5 volts. This cannot be presented as a valid simultaneous operating window, and the signs should not be silently reversed to create a guessed specification.
What remains useful
A high sensor voltage is electrical evidence, not direct proof of excessive hydraulic pressure. The reference-supply fault exclusions also show why supply status matters before interpreting the sensor signal.
Verification requires the correct service calibration to resolve the enable conditions, then a completed high-signal test on the identified channel. This draft remains needs-review because the published reference-supply conditions are internally inconsistent. It does not recommend a pressure sensor or controller replacement solely from the code.
Documentation and applicability
These details describe the monitor in GM’s 2025 25OBDG07A Part2 file. Its application-matrix filename does not match the download index, so model and engine applicability remain unresolved. Use the vehicle’s correct service information before applying these calibration details.
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 Pressure Sensor/Switch C 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