Ok, so I've had my check engine light on for 4 months reading codes 14 and 25. I replaced my O2 sensor and have had NO CODES for two weeks. Ahhhh, sweet victory!

 

any difference in the running of the rig?

 

x2 ^

noticable mpg change?

 

Before the change my acceleration felt sluggish, like it wouldn't accelerate even if I gave it a little more gas. Now it accelerates in my opinion like it should, so I can drive around town with a light pedal.
I'm expecting better mileage, probably 10%, just based on the performance change but it's not my daily driver so it may take a while to go thru a tank of gas.
Two months ago, with the old sensor, I worked it out to be 15.2mpg.
Will post new figures when I got em.

 

Okay here's the goods, my new miles/gallon is 16.6, up from 15.2.
That's 8.4% better mileage than with the faulty O2 sensor.
Not astronomical by any means but an easy perk up.

 

do you have to reset the ecu after you change the O2 sensor? disconnect the battery for a little while.

 

I didn't reset it, but the check engine light went out on its own. Didn't disconnect the battery.