Well I was driving today from work and Service Engine Soon light came on and stays on. So on the way home I stopped by Gladstone Mitsubishi here in Manchester NH (they are closing their doors by the way end of this week) and technician there ran a quick diagnostic which came up with an error code P0402. He told me this code stands for Catalyst Efficiency Below Threshold. Now I have to find a different dealership to take my car to get checked out.
My car is stock with 9500 miles on it, wouldn't expect to have catalyst problems even years from now.
I was wondering if anybody here had this problem?

 

P0402 or P0420 ?
P0402 is an EGR code. Ive seen this when the vacuum line pops off.
P0420 is the Catalyst Efficiency Below Threshold code. It usually means the catalytic converter is not working/missing. I have seen a few fail early in their lives. Car is stock so you shouldn't have a problem getting it replaced at the dealer.

 

It's P0420 sorry for typo.
Is it ok to drive it like that until I find a dealership to look at it??

 

I wouldnt. I had the same problem. The car lost ALOT of power and just didnt drive correctly. Of course the dealer fixed it and now its all good

 

I've never heard of people having a loss of power for a P0420. I am by no means an Evo ECU guru though so this is interesting.

To the OP I don't feel there would be any problem driving with it like that. Until the ECU gurus came up with the ECU mod to fix the SES light for test pipes, people would drive them around like that all the time. Now if your front o2 goes out then you will notice a serious drop in gas mileage but not an issue that would cause a loss of power.

Josh

 

Went to Nashua Mitsubishi dealership today and they confirmed the code P0420. They ordered a new cat converter replacement which is under warranty of course. Thanks all for the input.

 

My guess would be the rear oxygen sensor not the cat.

 

would this be because the stock a/f setting are really rich and can shorten the life on a cat?

 

I vote o2 sensor as well....

 

I ran with that code for about 2 months, replaced the stock cat with high flow and got it again... It has been on for about 2 more months, and there is no loss of power for sure... you can clear the code by unplugging the battery but it will come back after 5 miles of driving...

 

Ya I would say the sensor to. Only because its electronic and the cat failing is so highly unlikely with 9k.

 

You can get anti-foulers from RRE that you can put on your o2 sensor (behind the cat) and that will help you from the sounds of it.

 

I'm also throwing this code. I do not feel any loss of power, and my gas mileage seems to be OK. My Evo has 25k on the clock.

What does a new catalytic convertor go for these days from a dealership? And if it is the O2 sensor, what's the cost on those?

 

Exhaust leak? Stock so asuming you have a cat in the car. The dealer has to fix the problem 100% for anything that is emissions related