Possible causes

– Low transmission fluid level
– Dirty transmission fluid
– Faulty shift solenoid ‘E’ valve
– Shift solenoid ‘E’ valve harness is open or shorted
– Shift solenoid ‘E’ valve circuit poor electrical connection

Tech notes

When the a transmission solenoid is stuck off, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is very dirty, it is recommend changing the transmission fluid and if possible removing the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a transmission mechanical failure and that the transmission will need to be rebuilt or replaced.

When is the code detected?

The P0771 code is detected when the ECM has detected a mechanical fault with the solenoid energized, valve stuck off

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Transmission will not shift gears.

P0771 SUBARU Description

Shift solenoid valve ‘E’ is turned ON or OFF by the Transmission Control Module (TCM) in response to signals sent from the park/neutral position (PNP) switch, vehicle speed and Engine Control Module (ECM) (throttle opening). Gears will then be shifted to the optimum position.