My SES light just came on yesterday while on boost on the highway. I just got it scanned @ autozone and P0300 + P0138 codes came up. Can the rear o2 sensor cause a misfire or vice versa? I was wondering what I should try to fix this. Thanks

 

Joys of owning an Evo... Search P0300... Tuning will solve your problems..

 

I'm a broke college student Any other way that doesn't require $200+? I was told to unplug battery and see if the SES comes on, if it doesn't then forget it?

 

Unpluging the battery is only going to reset your ecu, it's not going to fix anything. You have the 138 code because your rear o2 sensor is dead or you have a catless TBE without a cel fix, or your cel fix isn't working right.
It's not as common for the IX to get the p0300 code for no reason like the early 8's did... I think you would be ok resetting if the car is running fine and you are already tuned for your current mods. If the car IS running like crap, then you have a problem, could be bad spark plugs, coils, boost leaks, issues with fuel delivery ect., and you don't want to keep driving the car until you resolve the problem. Evo's and college students don't always mix that great, haha, they are a money pit.
Unplug it for a min, hook it back up, start the car, take it around the block driving normally, and report back.

 

Well, after unplugging the battery the SES didn't come back on and the car seems to be driving normally. This is my 2nd week of ownership and already threw some codes what a bad start. I dont know anything about my car except that it has 40xxx miles, a oil cooler, aftermarket clutch, and a aem intake everything else is stock. It was from Exotic Motors in Rolling Meadows, Illinois anyone know this car? http://www.exotic-motors.com/detail-...d-5415711.html

 

Funny, I live down the street from that place.