P0777 Pressure Control Solenoid B Stuck On

P0777 indicates pressure control solenoid B is stuck on. The transmission hydraulic pressure behavior suggests the solenoid remains applied when it should release.

Code details

Generic OBD-II · P0

System: Transmission
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace internal transmission parts before checking pressure-control solenoid operation and valve-body contamination.

Symptoms of P0777

Harsh, delayed, or slipping shifts, or being stuck in one gear.
Check-engine light, sometimes with limp-home mode.
Flaring RPM or a shudder under load.

Common causes of P0777

Low or degraded transmission fluid.
A failing speed sensor, shift solenoid, or pressure-control circuit.
Wiring, connector, or internal hydraulic/mechanical faults.

Useful checks before replacing parts

Monitor commanded pressure, slip data, shift timing, line-pressure data if available, and solenoid B state.
Check for valve-body sticking, debris, contaminated fluid, solenoid mechanical sticking, or wiring shorts.
Review harsh-shift, delayed-engagement, or limp-mode symptoms with companion pressure and ratio codes.

Related OBD-II codes

These nearby transmission entries can help compare wording and pin down the fault area.