My check engine light came on and I got codes 0303 and 0304 for front heated O2 sensor, and knock sensor. Is this something that I can fix myself or do I need to have it checked out at a Nissan dealer? Any help would be appreciated.

 

Replacing an Oxygen Sensor is something which can be done by the novice home mechanic.

I suggest you defer action on the Knock Sensor. These two codes are often observed together and replacing the Oxygen Sensor may resolve both Codes.

 

Thanks for the quick reply I'll see what I can do.

 

is there a how to any where on-line on changing the O2 sensors? Or should I just go buy the Chilton manual.

 

The Chilton and Haynes repair manuals are good value for the home mechanic. Haynes is the better of the two. Either one will be money well spent.