Q&A

I have 'Check Engine Light' on (OBD Code P0740) about a year, my car is running OK, except slightly low fuel economy (19 Miles/Gallon). My questions are: 1)Could it be just Solenoid problem or bad Torque Convertor (need to rebuild Transmission)? 2)if it's Solonoid problem and I keep driving without doing anything, will Transmission go bad eventually? 3)To rebuild Transmission will include Solenoid replacement? 4)Usually, what's cost to fix this kind of problem? Any suggestion would be much appreciated!