My girlfriend has a 97 Z and has had a check engine light for the downstream o2 sensor for awhile and i just replaced it around a week ago. I thought it would help her gas mileage because it was pretty bad while the dummy light was on, but it seems like there is no change. Also, no other codes have come up since it was changed... anyone have any ideas of what could be causing her gas mileage that wouldnt set the light?

thanks for anyone's help!

Clogged air filter
under inflated tires
brakes dragging
driving with one foot on the brake
bad driving habits, quick starts, fast stops
Extended idling time, morning warm up, drive thrus, extreme traffic, just waiting with the car running and AC on
need of a tune up
slipping clutch / slipping auto trans
excessive engine wear / poor compression
bad wheel bearings
clogged injectors, stuck open
windows open
clogged catalytic converter



how many causes for decreased mileage would you like?
Could be one, could be a combination of several

Dave

well, i'm not a dumb ass! haha

everything you posted is fine... the only thing i would have to check is the injectors