I had a hard-start problem and a miss in my gta (problem later determined to be a POS ACCEL ignition module ) and i borrowed an auto x-ray to make sure everything was ok. well when the car is warmed up and in closed loop i was monitoring the Oxygen sensor voltage while i was cruising and it seemed to vary a lot. the x-ray reads updates the voltage reading pretty fast but i was still seeing it jump between .1-.2 volts all the way up .8. The sensor is fairly new. Is the oxygen sensor supposed to do this or is the voltage reading suppose to be relatively constant and "smooth"???

 

Don't worry, it's supposed to do that....

 

Ditto, working fine.

 

Yes, I concur. My Autoxray shows that my O2 sensor is changing from 100 some Mv up to 900 some Mv.

 

If it does not go high-low then you have a problem.