I was driving south with the family to Miami when after filling up and continuing down the highway, the SES light came on. Went to one of the big chain stores to see what the code referred to and it is P2A00. The O2 sensor. So I know that I'm probably going to have to see if there's a leak and/or see if the O2 sensor(s) failed. I do have mods, ART PIPES, stillen headers, XYZ pipe, and an Osiris tune. Any advice from those who hold reputable mechanical knowledge of the G35?

 

You pretty much nailed it on the head. One of those two

 

If you are involved with tuning yourself, you should look into an upgraded aftermarket o2 sensor for more accurate readings.

 

Please elaborate

 

I went to the local tuner today... Guess I should've just asked you first -.-

 

As long as you're not in an 03 the factory widebands are more than sufficient for tuning. Built motor/ high HP builds of course are different..