Have any of you ever heard of this. My folks took thier car in and thats what they said had to be replaced. Is this a load of BS?

 

Yes...generally when this goes out the tach will act funny and/or quit working. It also will affect timing a bit. Sometimes when its cold you will get a backfire between shift and such. They do go out, i had to replace mine when i did a motor rebuild and put my cam/heads in....my tach just stopped working