hey guys, today i went and had the oil changed in my car, and before they did it the mechanic came and said my knock sensor was unplugged and asked if i wanted them to plug it in, so i said yes. my question is, is there any purpose for it being unplugged and if so what? thanks

also does it hurt it to be unplugged

 

if it's unpluged the EST would never get a signal from it to retard the timing for knock. there is no good reason to have it unplugged.