P0777: Pressure control solenoid B stuck on
Pressure control solenoid B in the automatic gearbox seems to stay permanently active. Debris in the fluid or the solenoid itself is usually to blame.
| Code | P0777 |
|---|---|
| System | Engine and transmission |
| Group | P07xx, Transmission |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P0777 means
The transmission control unit sees the pressure governed by solenoid B behaving as if the solenoid were always energised, whatever it commands. That changes how hard the clutches are applied. The exact job of solenoid B depends on the manufacturer.
Most common causes
- Dirty fluid with particles jamming the solenoid
- Incorrect fluid level
- Solenoid wiring shorted
- Pressure control solenoid B stuck or failed
- Valve body fault
Symptoms
- Engine or gearbox warning light on
- Very harsh or clunky shifts
- Gearbox goes into limp mode
- Jerky pull-away from a standstill
Can you drive with P0777?
With care You can drive carefully, but harsh shifts punish the gearbox and it may go into limp mode. Get it to a garage soon.
Open the bonnetthe in-depth explanation
How to check it
Note whether the harsh shifts happen when cold, when warm or all the time; that detail helps the garage a lot. Check the fluid level and colour too.
How to read and clear P0777 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0777 with its description and whether it’s confirmed, pending or permanent.
This code is usually stored by the gearbox control unit. If the car reports it over standard OBD, you read it for nothing with FREE; to read it straight from the gearbox control unit, with its description and clearing, you need PRO.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P0773 Gearbox shift solenoid E has an electrical fault
- P0774 The gearbox solenoid E fails now and then
- P0775 The pressure control solenoid B is not working properly
- P0776 Pressure control solenoid B: performance problem or stuck off
- P0778 Pressure control solenoid B has an electrical fault
- P0779 The pressure control solenoid B fails now and then
- P077A The output speed sensor has lost its direction signal
- P077B The output speed sensor circuit direction is not working properly
- P0700 Transmission control system: fault detected
- P0701 Transmission control system: range/performance
- P0702 Transmission control system: electrical fault
- P0703 Torque converter/brake switch B: circuit fault
What does code P0777 mean?
The transmission control unit sees the pressure governed by solenoid B behaving as if the solenoid were always energised, whatever it commands. That changes how hard the clutches are applied. The exact job of solenoid B depends on the manufacturer.
Can you drive with P0777?
You can drive carefully, but harsh shifts punish the gearbox and it may go into limp mode. Get it to a garage soon.
How do you clear P0777?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0777 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
