I just fixed my 1999 Nissan Quest oxygen sensor error code with grounding bypass. Please refer to Nissan TSB-NTB99-004B and this YouTube video (
Nissan truck o2 sensor code FIX! *CHEAP* - YouTube). This problem bothered me a couple of years and I replaced three front oxygen sensors and a bunch of parts with no use. Now, my Nissan works like a charm!
Oddly, 1999-2002 Nissan Quest has the same engine as its Pathfinder and Frontier, but Nissan didn't put this TSB to Quest.