I have an 03 and never had an issue with the P0300 bug, until now.

I was driving home from work today and got off the highway and was sitting at the red light and my SES light came on. Went and read the code and it was P0300. The code stayed on while idleing and driving to AutoZone to read the code.

I adjusted my cam gears on Saturday (about 50mi ago) and that is the only thing I can think of that would cause this. They were set at 0/0 but now at -1/-4

Any suggestion as to why it would come on after 22k miles???

 

The change in cam gears could definitely be part of why you're seeing this. Not all Evos do this, but it seems the further you vary from stock cam timing and ignition timing, the more likely you are to see this code.

I've done alot of testing and the things that seem to affect this most on my car are: gas quality, spark plug condition, and cam gear and ignition timing settings.

 

I got this code for the first time at about 23k, and was a little worried about it. It ended up actually being helpful. My plugs were in pretty bad shape and needed replacement. Before you start worrying that you have the PO300 plague check your plugs, they may need to be replaced.

-Paul