Transmission Control System Malfunction PONTIAC GRAND PRIX....?

[Jonathan]

HI I HAVE A 1998 GRAND PRIX SE 175,XXX MILES FIRTS OF ALL CHECK ENGINE LIGHT ON TOOK IT TO GET SCANNED TO CODES CAME UP TEMP SENSOR HIGH IMPUT...I CHANGED TEMP SENSOR AND STILL CODE OMES UP FOR THAT...SECOND CODE AME UP FOR Transmission Control System Malunction IS IT SOMETHING THAT AN BE FIXED A SENSOR?????IM GONNA TAKE IT TO A TRANSMISSION SHOP IN TOWN BUT I WANNA KNOW IF THE Transmission Control System Malfunction IS A BAD THING TO POINT IMMA NEED A NEW CAR????