O2 sensor
 

Today i replaced the O2 senson on my 1989 560sl in the process i fond that the sensor was not hook up the cables were just not connected, i will try it an see if it runs diferent now, the question is should the c/e ligth be on, acctually it looks like is not working, do i have to take the wheel of to get the cluster out to check the bulb?. I would gess the reason the did it is couse we did not have unleaded until a couple of year ago an you know what happens to the cat if you run lead. any ways i am using unleaded now but i still don have a cat, an not thinkig about gettin one.

If you aren't running a cat, then there is not a lot of reason for using the O2 sensor. Your car wouldn't have a check engine light. If it was a US model with cat it would have had a O2 sensor light. It should light when the sensor is disconnected for a time.