O2 sensor operation

[john carroll]

My GM manual 16009.?0-1 indicates on page 5-9 and 5-10 that  normal
operation is for the output voltage to cross the .45 volt reference signal 
quite often.  If it stays above or below for "too long" an error code is set.  
My personal observation is that the it does indeed cross often.  an error 
code is also set if it stays between .3 and .6  with no crossings.  Proper 
operation is to cross .3 and .6 "often"  I doubt that it is possible to bias 
the operation by skewing the output of the  sensor.