OXS and poor mileage

["Rob Winchell" <rbw@avs.com>]

Q -

This morning I installed a new oxygen sensor, after I decided my old one was
shot. I am happy to report that the car is now running much better, where it
was once running rough and hesitating and "searching" under load.

Unfortunately (and to my surprise) my mileage seems to have DECREASED after
the installation. What's up with that? I am now getting horrendous mileage,
like 15 city / 20 highway (not being a leadfoot, either).

Any ideas on why this would happen? Is the ECU baffled by the new OXS? Any
ideas would be appreciated.

Rob Winchell
91 200Q