Trying to identify a sensor connected to my filter box

Just replaces my radiator and heater auxiliary water pump finally got it all together on my 2006 XJ8L and now I have a wiring problem throwing codes saying plugs firing intermittently. when I put all the wiring back together I had this sensor that i’m guessing was connected to the filter box because it lines up with the two different size holes in the filter box edge however it looks like it should be connected to another plug but for the life of me I can’t find another plug end. Anyone know what this sensor? is?

I think the sealing bungs mean it’s never been used

Thanks Andy that makes sense. Now I have to figure out what connections
i disturbed to cause the plug malfunctioning my computer says its always
plugs 2,4,6 etc. that are misfiring but only after running great for
about 45 seconds to a minute which ordinarily would make me believe its
either gas or air starvation on that side

Dennis Cunningham

1986 XJS-C 53,000 miles

2003 VDP 103,000 miles

2006 XJ8L 83,000 miles