Ummm, follow the manual and set it correctly?
Seriously though, we really need a bit more info than code 7 and should you replace it! What's been done to the truck? What are the symptoms? How long have you had it? Have you tried setting it properly?
There's about 5 thousand other questions I could ask before anyone would be able to give you a straight answer, but if you haven't set the tps correctly, buying another one and slapping it in will do absolutely nothing for you. It has to be set correctly for it to work correctly.