What kind of mv are they supposed to fluctuate from?

Both of mine are going from 420/450 - 750-820mv. At Idle... is that ok?

 

They should fluctuate from .000 to 1.000 volts. But I think your readings are just fine.

 

Those readings do not sound right to me. They should fluctuate from a lot lower than mid point.

Something like 30 to 800..... up and down, up and down ... etc.


Make sure your engine has been warmed up properly before you take the readings because the 02's take a couple of minutes to warm up on warm weather. I imagine they take longer in cold weather.


Marvin

 

They are definitely warm... The car was at normal operating temp and then sometime afterwards.