P0777
Pressure Control Solenoid B Stuck On
Transmission
Generic OBD-II
Medium
What it means
P0777 means pressure control solenoid B appears stuck in the on (open) position, so it keeps applying hydraulic pressure when it should release. That can cause harsh shifts, slipping, or the transmission stuck in one gear. Contaminated fluid and debris are frequent culprits, so checking fluid condition is the first step before condemning the solenoid.
Medium
Can I keep driving? Usually drivable, but a stuck solenoid can cause harsh shifts or the transmission stuck in one gear — repair soon to avoid overheating and wear.
Common symptoms
What you'll notice
- Harsh or delayed shifts
- Transmission slipping or stuck in a single gear
- Transmission may drop into limp mode
- Reduced fuel economy
- Check-engine light on
Common causes
Most likely first
- Pressure control solenoid B stuck open (mechanically jammed, often by debris)Likely
- Contaminated or degraded transmission fluid holding the valve openCommon
- Damaged wiring or corroded connectors in the solenoid B circuitCommon
- Sticking valve body boreLess often
- Failed transmission control module (TCM)Less often
How to diagnose & fix
Work through it in order
- Check transmission fluid level and condition first; contaminated fluid is a common cause of stuck solenoids — service if dirty or burnt.
- Read freeze-frame data and inspect the solenoid B connector and wiring for damage or corrosion.
- Test solenoid B electrically and, where possible, verify it can move freely; replace it if stuck or out of spec.
- Inspect the valve body for a sticking bore or debris.
- Clear the code and road-test; suspect the TCM only after the above pass.
FAQ
Quick answers
Is it safe to drive with P0777?+
Short trips are usually fine, but a stuck solenoid can force harsh shifts or hold one gear, adding heat and wear, so repair it soon.
Can I just clear P0777?+
You can, but if the solenoid is physically stuck or the fluid is contaminated the fault returns quickly.
Related codes
Often seen with P0777
Read & clear P0777 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX