I have a 1994 E320 Mercedes Benz. The check engine light came on and the MB mechanic determined that it was caused by a faulty Oxygen sensor. Would using a midgrade gasoline cause this problem? It says to only use premium gas and I filled the tank with midgrade and shortly afterwards the check engine light came on. Was that the cause or was it a coincidence?
Thanks, Bill Scott

Midgrade or premium has nothing to do with an O2 sensor.
The only thing that can ruin it in short order is leaded gasoline, which has not been available for many years.
Leaded gas would also destroy a catalytic converter.
I believe it is just time, after 10 years, for a new sensor.

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2007 C 230 Sport.

If you look at service recommendations, most will say to replace the O2 sensor at some point. I always wait till they fail, but failure can come from many reasons. Various silicon gasket sealers contaminate sensors, antifreeze contaminates the sensors and carbon in the exhaust coats them till they see nothing.

With that said most O2 sensor faults are something else.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician