google lean burn oxygen sensor and do some research, but looks like that constant 0.45 is good 
on September 2, 2012, 9:31 pm, in reply to "Re: Toyota Avensis 1.8 1999 poor Lambda behaviour"
Les comment re Toyota sensor has reminded me that Toyota used a unusual and unique sensor I think it may be simple wide band sensor,introduced about that time. (Edit I think toyota called this a lean burn sensor.)
hopefully some one more knowledgeable will give better information on its working and expected signal output.
It could possibly explain your unusual sensor output
I remember that for a long time these sensors suffered from failed heater circuit and where not available on the after market, but I have more recently success with blue print vehicle specific units
Cheers Aidan
I
