If yuur replacement O2 . . . .
sensor is like mine (and I think it will be), you'll find that it has a very long connecting cable.
If I remember correcrtly, MB doesn't make that 'version' any lanoger but a 'universal' one that fits a number of cars. You will have to fold the cable back onto itself and use cable ties (perferred) to get it to the right length.
The difficulty with this longer folded-back cable is that it wants to droop abit and it could rest on the exhaust pipe, a definite no-no. Other than that it will really improve your car's performance and gas milage.
About 8 months ago, I replaced my MAF and O2 sensor. Since then the gas milage has been around 15.5mpg city and close to 20mpg freeway.
Also the fuel computer's S/A has gone to 0.9091 from 0.8389. I have my DTC#19 eprom in my car. But this is a very expensive solution: MAF price was $290, O2 was $78, wholesale prices.
Regards . . . . JimF
'94 S500 Cpe
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