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?
>

2. one staring you right in the face on the exhaust manifold, and one
after the cat, which is bolted to the exhaust manifold.

> She got a CEL, Autozone says their scanner cannot differentiate between
> a front or a rear O2 sensor failure.

they need a new scanner then. IIRC, my code was PO135 primary oxygen
sensor heater circuit malfunction.

primary means top, the sensor in the manifold.
>
> The front sesnor is about a year old.

OEM honda, or aftermarket? either way its worth testing the sensor for
continuity. for me, the 2 bottom black wires read 0 ohms, which meant
the heater circuit was dead. or something like that. id bust out the
ohmmeter and helm manual and test em both.
>
> Are there front and rear sensors, or is the Auto Zone dude all wet?

yep, there are. but front=top and rear=bottom
>
> The rear sensor price is about $250 (if there is such a thing).
>
> Tom
>