Heated vs non heated o2 sensor

[SmellyCat]

I read the 02 sensor does not work till it is 300degrees. I cheaped out and replaced the heated 02with an unheated o2 on my tail pipe. Did this hurt my mpg? 94volvo940 wagen. sC

[user removed]

I would think it would delay initial function. That's about it unless you are having other problems since installation.

regards
Mech

[SmellyCat]

Would the car run rich or lean while the o2 sensor was heating up. The engine seems to run fine. Sc

[GTR]

Probably just runs in open loop mode, which is likely richer than closed loop. It's running a pre calibrated ratio of air/fuel, rather than using the o2 sensor to adjust air/fuel on the fly to achieve the best ratio as you drive.