P0877 code meaning
Transmission Fluid Pressure Sensor/Switch D Circuit Low
What P0877 means
Transmission fluid pressure switches C and D report whether a clutch circuit is pressurised. They are more widespread than A and B: GM's 6L80/6L90 and 6T40/6T70 six-speeds put switch C on the 2-6 brake and D on the 1-2-3-4 clutch, Allison uses them for its third shift valve and its reverse switch, Ram's RFE gearboxes for the clutch pressure switches in the solenoid block. Ford reports pressure faults under its solenoid codes. P0877 means switch D reports pressure while its clutch is exhausted. GM checks the 1-2-3-4 clutch below 50 kPa commanded and sets it after 5 counts, without MIL. Allison 2007 uses it for the reverse switch reporting R in a forward or park range for over 1 s, type A with MIL; it then suspends the gear ratio checks.
P0877 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyHard
- Typical labor1.5 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0877
- Code stored in the gearbox module; on GM without MIL, on Allison with MIL
- Harsh shifts, possibly substitute gear
Common causes of P0877
- Most likelyPressure switch stuck closed or shorted internally
- PossibleSignal wire shorted to ground inside the gearbox
- PossibleClutch circuit does not exhaust: dirt, sticking valve
- Less likelyRange sensor wrong (Allison comparison)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Transmission fluid pressure sensorTransmission valve bodyTransmission wiringTransmission control module
What each part of P0877 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 8 | Area: transmission. |
| 77 | The exact fault in that area. |
What to do next
- Note P0877 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0877
What does P0877 mean?
P0877 means "Transmission Fluid Pressure Sensor/Switch D Circuit Low". Transmission fluid pressure switches C and D report whether a clutch circuit is pressurised. It is a generic code, so it means the same on every make.
Is it safe to drive with P0877?
Drive gently and only to a workshop. With P0877 the car can go into limp mode (reduced power) to protect itself.
Will P0877 fail an emissions test?
P0877 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P0877 to fix?
Difficulty: hard. A typical repair takes 1.5 to 5 hours of work. This is a job for a workshop.
Will P0877 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.