I just discovered that my car does not have anything inside PIN 3 for the emissions reading. (It is empty, with no metal contacts)...so how do i go about reading emissions on this car?

the point of all this is to see if my mixture is off causing a bad exhaust smell and possibly damaging the cat and O2 sensor ...

i would appreciate any insight on this

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1993 300E, 2.8 M104 .....