A post in the referenced thread in post #3 claims that only California models had the temp sensor.

NEGATIVE!

I special ordered my '88 190E 2.6 five-speed and took delivery from South Bay ********, the MB dealer next to Zamperini Field in Torrance, California. It doesn't have and inlet air temp sensor nor an air pump or EGR valve. Later model year M103s can have have all three.

Another post in the referenced thread said his '88 190E 2.6 doesn't have a catalyst, but he's a Aussie, so different configuration than USA and CA.

Duke

P. S. I have no idea why the dealer name was censored