P0778
Pressure Control Solenoid B Electrical
General electrical fault on the pressure control solenoid B circuit — open coil, short to ground or battery, or driver feedback outside the expected range.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Common causes
Ordered by how often each turns out to be the cause.
- Open solenoid coilCommon
- Damaged wiring at the transmission case connectorPossible
Parts involved
- Pressure Control Solenoid B
- TCM
- Wiring Harness
P0778 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.