This looks like it belongs around the rear-end of the block, underneath where its really difficult to see plugs, etc. I'd check under there first. You'll have to jack the car up, climb under it and scour the block for any connections that might be missing. If you don't see anything, then dont worry.. Just go to crank the car, and if it wont start or runs like crap, take a look @ what codes the ecu is throwing and thats your answer to the question.

GL man