i CHECKED MY 2000 NEON FOR ENGINE CODES AND THIS P0743 CAME UP AND I WANT TO KNOW WHAT COULD BE THE PROBLEM IS IT THE ELECTRICAL SYSTEM OR SUM OTHER THING AND HOW MUCH WOULD IT COST TO REPAIR IT.

P0743 Torque Converter Clutch/Solenoid Trans An open or shorted condition detected in the torque
Relay Circuits converter clutch (part throttle unlock) solenoid control
circuit. Shift solenoid circuit C electrical fault-Aisin Trans

 

Probably a torque converter clutch solenoid. Now the question is can you change it in the car that I do not know. Basically it sounds as if you are not going into lockup probably hurting your gas mileage. It in itself is not hurting your car, just your walet. But price to fix not sure myself.