"Woody" <TheDuck@pond.net> wrote in message
news:8s33g.69065$H71.136@newssvr13.news.prodigy.co m...
> Am 89 is not OBDII compliant and does not monitor the sensors that close
> and the sensors are totally different. The OBDII system monitors heater
> current and voltage and switching times and voltage to very precisely
> determine what they are doing. The chance of them causing a problem
> without setting a code is extremely slim. They can be setting sub codes
> long before turning on the light on the dash. The information in the
> computer should be thoroughly analyzed as swapping parts is expensive and
> could just be masking the real problem.
>
>
I would have thought OBDII would catch O2 weakness, too, but as the Subaru
experience illustrates it isn't necessarily so. I am puzzled what sort of
out-of-the-box defect the sensor would have that would cause it to behave so
badly and not be tattled on, though.

Mike