P0777: Pressure Control Solenoid B Stuck On
What to do
Expect a jolt on particular gear changes, worst when driving gently. Not usually harmful to the gearbox itself, but worth diagnosing rather than accepting.
What this code means
Pressure control solenoid B is holding its pressure high rather than modulating it, so the shifts it governs land hard. As with P0747 the transmission is not usually being damaged — excessive pressure applies a clutch more firmly rather than letting it slip — but the shock is transmitted into the driveline and the harshness is unpleasant enough to warrant repair.
Likely causes
Start here
- Faulty pressure control solenoid · moderate
- Stuck valve in the valve body · specialist
- Debris in the transmission fluid · moderate
Less common
- Wiring shorted to ground · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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