If the car engine problem is general or serious, then you should solve the car engine. Do not ignore any problem in the car engine. The car engine P2789 Code is found from the car engine and solve the car engine as soon as possible. There are some common reasons what include imperfect clutch components, a faulty electronic compression control solenoid, hydraulic blockages inside the internal transmission fluid passages, mechanical internal transmission displeasures, low transmission fluid, dirty or polluted transmission fluid, a faulty PCM or transmission control module. The symptoms of the car engine problem helps to know the real problem of the car engine.