Jeff,

I'm having what I think are identical issues with Bank 1 on my 97 S600 sedan. I have an O2 sensor, which I think is the pre-cat sensor, that is flat-lined at low voltage. I'll have to hook up my scanner again and re-confirm which sensor it is. New O2 sensor did nothing to the bad signal on the OBD2 scanner. Swapping MAF's and O2 sensors between banks did nothing. I'm close to beginning the hunt for the root cause of this problem since I'm now having a high, surging idle issue that began with removing and cleaning the throttle bodies. grrrr. That was supposed to be a good thing to do, but it seems to have caused some problems...

Brett

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1997 S600 sedan