On pass. side under floor mat, i found this part measuring 1"x2" with a plug on one side and a 1/8" dia. peg with a hole in it on the other side that apears should have a vacuum line on it but doesn't.Part numbers are:0 280 101 003 also 006 542 50 17.

If one end has wires going through the transmission tunnel it's part of the oxygen sensor wiring.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

It is located on the upper left side of the pass. floor. The wires go up and out into the engine compartment. My concern is if a vacuum line is missing.

It is the air temp sensor for your cabin, climate control uses it to monitor the inside temp of the car. I do not believe it has any vaccum line connected to it, my 420 also do not have a vac. line to it.
I hope this helps.
Thanks

__________________
87 420 SEL
Looking for a nice mid 80's MB diesel.
87 BMW 528e (Sold)
99 TOYOTA 4Runner
1989 Honda Accord (Sold)
1988 Honda Accord (Total)

Thanks SIXTO,BENZMATIC: I thought i had a vac. line missing.