Honda CRV 2008, Engine Light is ON, with Blinking D

Question

speedometer is moving while the car is stationary, i can not go to higher gears, say 3rd and above gears. also D is flushing together with check engine light is On.
on OBD2 scanner it shows code U0122.
they pulled off engine recently to insert Gearbox Oil seal which was leaking, after fixing back the engine this is where all these started.
also AC is not working but if you start it manually by giving it power straight from the alternator it runs..