These are great cars! I am having fun hearing you discover these things.
They are yellow for several good reasons: The yellow doesn't offer as much "glare-back" in fog, where of course these lights are typically used. Also, driving with your yellow fogs on, even all the time, makes your car more conspicuous in traffic (noticeable if you will). If you change them to a "white" light and turn them on, most "American" drivers will automatically think you have your brights on and flash the hell out of you. I recommend staying with the yellows. I had a car where someone changed to the whites and after a while I converted them back to the yellow.
Yes, the empty socket is most likely the rear fog in the left-rear tail light housing. I forgot which bulb it requires, but you manual I believe will list it. DONT buy a cheapo bulb. Go to a parts store that sells OEM bulbs. They are often in a silver metal casing instead of the typical brass.
Get the right one or your bulb-out indicator will go on and you'll think you've got wiring problems. Did I say "Get the right bulb"?
Now for fun, discover how to make your hood open full vertical for easy access to the engine and fuse box.
I sometimes, when waiting for someone in the car, will pull out the manual and try and find something new that I donít know about the car. I am embarrassed to say it, but often I will find something I didnít know. The more I learn about these cars the more I like them.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)