OXS function / performance

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

Q -

I got my car back from the garage yesterday and they had forgotten to plug
the oxygen senson and heater back in (they disconnected it to get at
something else). Caused the "Check Engine" light to go on, but other than
that, the car seemed to run great. When I plugged it back in, it wasn't
running as well.

Now, I guess I would expect this since the car was running rich when the OXS
was unplugged (right?). Thing is, I was getting better gas mileage WITHOUT
the OXS. This doesn't make any sense to me at all. Is this the sign that the
OXS is bad, that the car is insane or I'm just totally confused?

Thanks,
Rob Winchell
91 200Q
87 4kCS