P1744

I was sold a car yesterday, it passed emmissions this morning but this afternoon the check engine light came on with a code P1744, which after researching I know can be several problems. We had to add two gallons of antifreeze this morning due to it being empty, once we did that the heater worked fine. There is a whinning noise while running the car and it seems to eat gas a little faster than a v6 car should. Is it possible it may just be needing routine maintenence or is it more likely a problem with the transmission. The guy who sold me the car says it is not a problem with the transmission although the code states it is. Please help.