Hi so i have a 2004 mitsubishi montero limited and i got a check engine light with error code p0431 - warm up catalytic efficiency below threshold (bank 2) and someone recommended that before i switch any sensors or anything to try and clean it with seafoam. I cant seem to locate a vacuum line that is both easily accessible and gets to all cylinders. Could anyone let me know which vacuum line would be the best for this? Also any common causes for the error code would be appreciated. Thanks so much this forum has been loads of help!

 

Don't do it. The Seafoam "cleaning" does absolutely nothing for the engine and especially for the catalytic converter.

 

Oh ok! That saves me 9 dollars haha thanks! Is there anything that would clean it?

 

No, nothing will truly clean it. If you do not live in the place that requires emission testing, you can put O2 spacers on the post cat O2 sensors. That will take care of the P0431 code. Besides that the only option is replacing the Y-pipe with cat converters.

 

You might try CataClean.

http://www.cataclean.com/

 

Nope. Doesn't work. Same reasons as Seafoam.
Just think about it - when you put in a petrochemical into a combustion chamber and ignite it - what comes out?..
99%+ CO2 and H20 - same thing that comes out when you burn gasoline. If your gasoline did not "clean" the catalytic converter, why would the other petrochemical?

I had P0431 code. Never trusted the "magic" cleaners before, but got convinced to try it. Tried CataClean - no difference. The code was back in a day. Not trusting the "magic" cleaners ever again. I'd say - save your money.

Speaking from experience - unless you have a one/two year old vehicle and somehow oil got into exhaust/cat converter, the "cleaners" will do absolutely nothing. The efficiency of catalytic converters is reduced over time (on older vehicles) because the metals (catalyst) which sit on the surface of the honeycomb inside the converter get stripped away over time and there are simply not enough of them left to keep the efficiency at high enough levels. So called cleaners do not deposit any new catalyst on the honeycomb and thus can not improve efficiency.

 

I am in same predicament. My 2001 Monty XLS CEL comes on, and P0431 is on my OBDII reader. I put Pass4Sure in the tank, and right after 60 miles, the darn CEL came on... right before I was going to take it to CA emissions test. All I really want to do is get the light to turn off for about a week/hundred miles and take it to emissions so it will pass. CA emissions, since she is 2000 or newer, only has to be inspected and have the computer read. They don't hook it up to the dyno.

How can I get it to turn off for just a week - long enough to get her inspected? I don't really want to pay 1400 dollars for a new Cat, only to have the CEL come on three months later with some other issue.

I saw a post about seafoam in the oil and PCV. Not sure what he was referring to, since he had sport model. Does anyone know about that? Surely it would not hurt to try. And when you guys do that, do you reset your codes, or remove the battery to do so. Can they tell you reset your codes at the smog inspection place?

 

The p0431 code is a catalytic converter code...if you have more than 100k miles on the truck it means it's probably dying as what HunterD said. Maybe Cataclean will work for a newer car if the cats are plugged with deposits or something but won't do any good for a dying cat.