Fault codeP0778

MODERATE

Pressure Control Solenoid B Electrical

What this code means

Pressure Control Solenoid B Electrical.

P0778 is a generic code: it means the same thing on every make. P0778 belongs to family P07xx — Transmission. Its page explains how to read a code and groups all its codes by part.

Gearbox pressure control solenoid

Pressure control solenoids regulate the hydraulic pressure inside an automatic gearbox, which sets how firmly the clutches engage. The control unit drives them with a variable current according to the load and the gear.

What you notice

Harsh, slow or slipping shifts, a gearbox in limp mode with a single gear.

How to check it

Check the fluid level and condition: dirty fluid can stick the solenoids. Then the gearbox connector and the internal wiring. The solenoids are usually inside the gearbox, on the valve body, and replacing them requires removing the sump.

What to do

Have it checked this week. The car remains usable, but the fault will not clear itself and will fail the roadworthiness test.

Clearing a code switches the light off but repairs nothing: if the fault remains, the code comes back. Clearing a fault code yourself →

How to read this code

PPowertrain
0standardised code
7Transmission
78P0778