Have you checked for visible signs of damage to surfaces where the leak is coming from? Or maybe its a defective part and you can take it back and try a different one?
I don't think they come pre-coded and they're fine threads and generally don't require any tape or sealer on them You could try that You might want to run a brush in the hole that you're screwing the sender into just to make sure everything is clear You could also blow it off with some throttle body spray or something like that to make sure any residue and bull that's in there Is now cleared and there's nothing If I was going to try anything I might put some sealer on the threads not the tape they make some for automotive pipe sealing. You sure it's not the cover itself and then usually when these things leak the hermetic seal is broken between the plastic where the electrical connection is made and the metal body of the sending unit It's usually not leaking around the threads
Somehow the damn hole cracked. It was not like this when I installed the sensor. I used a torque wrench on it to the specified value (11 ft lbs).