Cappa convinced us to move the sending unit away from the headers for a more accurate reading to the temperature gauge. Before you go monkeying with the sending unit location, if you've got a single-wire unit, put a potentiometer in line with the sender, then turn the knob. With the key in the on position, turning the knob should move your gauge. If it doesn't, your gauge is bad. If it does, you can figure out the resistance at a particular temperature and check the gauge manufacturer or factory service manual to see if it's operating correctly.