Hyundai Repair: Engine Line, hyundai elantra, oxygen sensor

Question
I have a 2004 Hyundai Elantra.  One day the check engine light came on.  I went to AutoZone and they told me the troubleshooting code was P0030 and that I needed a new oxygen sensor.  I checked my warranty book and realized that that part is no longer covered by my warranty so I don't have to go to the dealer.  My questions are: Was the diagnosis by Auto Zone correct? What will this typically costs to repair? By the way, the engine light will go off for a day or two and then come back on for a day of two.  It does not blink off and on.  Thanks.

Answer
P0030 indicates that there's a problem in the front oxygen sensor heater circuit.

Without testing the circuit and sensor, it's impossible to say with certainty whether the problem is in the sensor, wiring, or ECM.  In nearly every case of a heater circuit code, however, the problem is indeed with the oxygen sensor.

You should call some repair facilities in your area to get an idea of repair cost.  It'll vary greatly depending on the facility, the manufacturer and distributor of the part, and your geographic location.