I haven't replaced the temperature sensor because my temp gauge inside the car seems to work fine, I don't have a check engine light but I can still get a diagnostic. As for the wiring harness, I'm pretty skeptical that it is that because of the way the problem started. I left the MAS unplugged accidentally while driving the car, then when a plugged it back in, car went into limp mode and wouldn't go over 5MPH. Had a mechanic take it out of limp mode but fan came on after doing so. It has remained on ever since. That was about a year ago