Diagnostic article Generic OBD-II
P0877: Pressure sensor D low refers to the differential-pressure input here
P0877 in this GM table monitors the limited-slip-differential pressure signal below range, with an unresolved reference-supply enable window.
Read before applying this article
Documented application
2025 GM 25OBDG07A Part 2, specific documented monitor only. Vehicle, engine and calibration applicability require confirmation; application-matrix filename join is unresolved.
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.
P0877 is the low-circuit code for transmission pressure sensor D. GM maps this row to the limited-slip-differential pressure sensor. That is distinct from the main transmission system-pressure sensor elsewhere in the same table.
Low signal voltage is not measured low pressure
The established input boundary is below 220 millivolts, with 30 millivolts of hysteresis and a confirmation time of at least 150 milliseconds. The table requires the main battery supply above 8.75 and below 18 volts and excludes cranking and STOP state.
The VREF1 enable cells are contradictory: they print a value above 5.5 volts and below 4.5 volts simultaneously. This was verified in the rendered original and is not converted into an assumed corrected window.
Follow the correct reference rail
The row lists P0882/P0883 and reference-A faults P0642/P0643 as disabling conditions. Preserve those codes and the VREF1 context when reviewing why the pressure-input monitor did or did not run.
A generic sensor-D label does not identify a physical connector without the installed transmission mapping. Nor does a low electrical reading prove low differential clutch pressure or a failed sensing element. The applicable circuit procedure must resolve the source’s supply-window issue and distinguish the sensor, wiring and controller input. This monitor supplies a low-signal diagnosis, not a complete hydraulic repair decision.
Source and applicability
This explanation covers the cited GM monitor, not every vehicle carrying this code. The application-matrix filename does not resolve cleanly to this file, so no model or engine fitment is assigned. GM diagnostic table, PDF page 907.
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 D 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