The check engine light came on a few days ago and when I checked it, it showed 3 codes. The first one, I was able to look up and was the 0304 knock sensor, I hope I won't have to replace that as my hands are too big for it and I had to get my girlfriend to replace it on my old maxima.

The second and third codes however, I could not find information about:

0409 and 0413

Anyone know what these are? I have gotten the 0413 code before about 2 months ago...

Thanks in advance

 

Front O2 sensors (left and right)

 

Does anyone know how much these will cost and how easy they are to install?