Dear azhari and LarryBible:
The other ends of those 2 wires are already connected to the engine block, so I believe the open ends must be connected to something else. Unfortunately, I could not find anything around that have missing bolt/screw, except the fact that there seems to be a missing screw on the engine part near the wires as shown in the attached image, but it does not make sense because there's no reason to connect both ends of those wires to the same engine block.
Mr. LarryBible: please take a look at your 240D's engine compartment when you go home this weekend.
Thanks a lot!