Hi, have been wanting to replace o2 sensor for a while now. Every winter mileage is about 22 to 23 M.P.G and when there is a complete week of warm weather in spring it goes up to about 25 to 26 M.P.G. The only two things that I think are the cause is one the o2 sensor and two the gas is formulated different in winter. What do you all think, do you get better gas mileage in the summer and winter the M.P.G drops some? It's the original o2 sensor with 290,000 miles on a 95 Accord 2.2 liter VTEC motor, have read there is a heater element on the sensor so it does not dump gas in there, think thats how it works anyway. Thanks for your time.

 

Gas is formulated differently in the winter vs the summer, so that could be the reason you get a drop on mpg.

The O2 sensor has to be hot to provide an accurate value on the oxygen in the exhaust. The heating element helps warm it up faster, so the engine doesn't have to run rich to warm up the car. I improves emissions and fuel consumption for regulatory purposes.

 

I have to agree with PAhonda. But there's also another possible reason for the winter drop, and that letting the car warm up/deice while you're clearing off the snow/frost off it. I know my winter mileage drops off, but then I let it warm up while I clearing off the car.
As long as you don't have a code flashing the MIL light, you're fine. If you start to notice your summer mileage drop off, then you might want to look everything over (do a tune up).
Just might take on things.

 

I just saw your email about the used O2 sensors, just send me your address.