2004 Montero LTD with 150000 miles. Code P0431 come up about a year and a half ago first time when traveling outside my state. I did reset code just to clear check engine light and decided to check when I came home. I did forget about it. Code came up again about month later. Reset again. Noticed that code is coming on only when driving in rainy days after driving for about 10 minutes and mostly on state highways. When is dry there is no code even when you travel for hundreds of miles. Just passed emission test with out any problems but rain next day so code pop up again of course. Is that mean my catalytic converter is going bad only when rain? Anyone have this issue? There no other symptoms, truck runs nice and smooth even when code shows up.

 

The catalytic converter is just going out period. The error code will eventually come up even on dry days. This code does not affect how well truck runs, only indicates that emissions are getting up above acceptable level. You need to start planning on ether putting in a new catalytic converter or on doing one of the number of other Macgyver "fixes" to keep the CEL from coming on.

 

Thanks. Guess I better start looking for new converter. Seems like I have to get two converters wth Y pipe and I'm sure that's gonna be costly :-(.

 

Yes, you will need the Y-pipe. Do you live in the area where where you have to do emission testing?

 

Had a problem with my air con too. But I guess it was harder to repair, or I'm just not as smart as you're. So, as you might guess, my attempt to repair it myself had failed. Need to say that I don't understand much in mechanics. I like to drive, but not to fix. So I just sought help from ac repair st pete, and it was done. I wonder how you can literally make or repair something with your own hands. It's just beyond my understanding. Probably I should learn more about car repairing. Luckily, I've never faced with any troubles on the road, but I should be prepared.