Well tonight on the way home from the movies my Service engine soon light came on. I have 20,255 miles on the car with P2 and full 3" turbo back exhaust with HF cat and magnaflow. P2 has been programmed to optimize the exhaust. I just unplugged the neg term of the battery and restarted the car and the light is no longer on. Anyone know what may have caused this light to come on. I have had the exhaust on for over 5000 miles now, so I really can't imagine it being that. I also just in case clicked my gas cap one more click. I guess tomorrow I will find out if the light comes back on.

 

P0300. Welcome to the club!

 

You need to pull the code to see what it is. My SES light would come on and go off for the past several months. It ended up being a bad MAF.

 

PO420.....cat efficiency below threshold.

Normal with H/F cats

 

Yeah I'm guessing that is probably what it is. Though I am wondering why it took almost 5000 miles for it to finally come on and notice the HF cat. I'm bringing the car to the dealer Saturday for it's scheduled 20,000 mi service and if the light comes back on from now to then I will have them tell me what it is and I won't unplug the neg battery terminal.

 

I just got a SES light for the first time tonight. Car has 42k miles. Not sure what the code is yet. Sorry to say but this morning i just installed my Works DP... Anyone else get a SES light from a DP install?

 

Did you let your exhaust hang down while installing the down pipe?

If you did you might have stretched the rear O2 harness that's in the catback. hopefully that's not the case , but have the code pulled and find out for sure.

 

I had a Helix dp and now a WORKS dp and never got a SES either way. But at 20k, I did get a P0300.

 

Well after resetting the ECU by pulling the negative battery cable, the light still hasnt' come back on even after driving 40+ miles. Hmmmmm very odd.

 

That is how the P0300 is for me. It only happens every now and then - comes, goes and does not re-appear for weeks at a time.

 

Well that kinda sucks, but hey as long as it doesn't come on too often, I think I can live with it. I'll just keep disconnecting the battery and hope it doesn't come on more than ever few weeks/months because it is a pain reprogramming the radio channels. haha

 

It will go away after turning the car on and off a few times. Until it turns off, you will just have to live with the SES light being on. Alarming at first, but you get over it after a while.

 

We recommend finding out what is actually setting off your CEL. If you are local, we can check it for you free of charge.
If not, try to find a friendly Mitsubishi Dealer or purchase an OBD-II scan tool for less than $100 which will pull up most generic codes for vehicles made since '96. Then you will have the tool for life.

 

I end up resetting the ecu the next morning and the SES never came back on. Low coolant, problem solved.

 

P0420 error code.