F3 error code GE Profile Microwave

I got the F3 error code on my microwave, no mention of it in the guidebook. Searched and found that it has something to do with a sensory problem. Checked the parts for replacement and am not quite sure which part it is that needs to be replaced. Also, some parts were not available so does that mean they are no longer made or would I need to search another web site?:confused: Thanks for any help.