I have a Dynojet 200 model with the air fuel Anilizer. I was using it today, everything was working great, all of a sudden my air fuel bar went to full rich and would not move after that, I'm guessing that it's probably the oxygen sensor but I figured I'd see if anyone else has run into this.

yea, unhook it from power and try blowing the wideband out w/ compressed air DONT USE CHEMICALS ON IT. somtimes gas and carbon from an overly rich vehicle will clog the diffuser passage.

after blowing out, let it hang in open air and power up the heater in it...it should clean out on it's own, but you might have to calibrate it again afterwards