<courir26@yahoo.com> wrote
> My daughter has a 99 Civic LX, California Model (LEV I think)?
>
> Does this car have one or two O2 sensors?
>
> She got a CEL, Autozone says their scanner cannot differentiate between
> a front or a rear O2 sensor failure.
>
> The front sesnor is about a year old.
>
> Are there front and rear sensors, or is the Auto Zone dude all wet?

There are front and rear sensors. You can go to Majestic's site
http://www.hondaautomotiveparts.com/ , put in the car's info, pull up the
exhaust manifold drawing, and see their location. The front one goes for
about $155 + s/h. The rear goes for about $194 + s/h.

Here's a nice summary description of what each does:
http://www.samarins.com/glossary/oxygen_sensor.html

IIRC, if the rear one fails, you risk destroying the catalytic converter,
which is expensive.

If the front one has failed, you should be seeing other symptoms, like poor
mileage, irregular RPM, hesitation, etc.


> The rear sensor price is about $250 (if there is such a thing).