So I've had my check engine light on for a while and i just now Got around to checking it and its code 31 (knock sensor) so I looked at the back ot my block and I don't even have one installed. So i kept looking and i found 3 plugs that are not connected one of which is taped to the harness . One of them has to be knock sensor but I'm not sure which one. And the other 2 I have no clue Wth they are for. Here's a pic . Any ideas??????