P0777 code meaning
Pressure Control Solenoid B Stuck On
Powertrain system Generic code P07xx codes Check engine light
What P0777 means
Pressure control solenoids are current-controlled proportional valves, and what B and C mean depends on the design: on GM's clutch-to-clutch automatics they are the pressure valves of clutches 2 and 3, on GM's CVT B is primary pulley pressure and C line pressure, on Jatco CVTs B is the secondary pressure valve, on Saab's AF40 B and C are clutch valves SLC1/SLC2. P0777 means the valve is electrically fine but pressure stays applied – the off-going clutch does not release. GM's 9-speed flags clutch 2 slip below 50 rpm for 0.8 s on loaded downshifts, the 8-speed uses a torque and inertia phase test, Allison 25 rpm or less – all after one trip. GM's Honda-built five-speed cannot always separate it from P0746 and stores both. Harsh shift jolts, tie-up and a default gear follow.
P0777 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor2 to 14 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0777
- Harsh shift jolt, transmission ties up
- Limp mode in a fixed gear
- Check engine light
Common causes of P0777
- Most likelySpool or pressure valve sticking
- PossibleClutch stuck or piston hanging
- PossibleContaminated fluid (debris after clutch damage)
- Less likelySoftware or false setting
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Pressure control solenoidTransmission valve bodyTransmission clutchesTransmission control module
What each part of P0777 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 7 | Area: transmission. |
| 77 | The exact fault in that area. |
What to do next
- Note P0777 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 P0777
What does P0777 mean?
P0777 means "Pressure Control Solenoid B Stuck On". Pressure control solenoids are current-controlled proportional valves, and what B and C mean depends on the design: on GM's clutch-to-clutch automatics they are the pressure valves of clutches 2 and 3, on GM's CVT B is primary pulley pressure and C line pressure, on Jatco CVTs B is the secondary pressure valve, on Saab's AF40 B and C are clutch valves SLC1/SLC2. It is a generic code, so it means the same on every make.
Is it safe to drive with P0777?
Drive gently and only to a workshop. With P0777 the car can go into limp mode (reduced power) to protect itself.
Will P0777 fail an emissions test?
Yes, it can. P0777 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0777 to fix?
Difficulty: hard. A typical repair takes 2 to 14 hours of work. This is a job for a workshop.
Will P0777 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.