Like I said a few posts up, I think you hit the nail on the head.

 

You are right, but no where do I mention what the actual code was I had, I was going by Catalyst System Efficiency description, not the #. And I may very well be wrong with the 1/1 designation for the 0420 code, I won't deny that.

 

Sigh. I'm almost sorry i got on this thread, we're dangerously close to (figurative) semantics now.

Here's an idea: I've got nothing to do today, so I'm going to take the non fouler trick off of my gutted cat. Drive around and see what code it pulls.

Fixin to drive a bit and get lunch, will post results

EDIT: just looked up a list of dtc's: 420, 422, and 430, and 432 are all basically the same. I suspect 3 of them are for cali emissions though. The word MAIN catalyst in their discription implies that there is more than one cat

Just thought id throw that out there, off to wrench and investigate.

 

Ya know, all you guys that live in a warmer climate, and blithely cruise out to your truck to do something or other, really get my Envy Up........

 

Me too! What part of, I said I could be wrong about the 1/1 designation as far as the P0420 codes goes? When ever I'm wrong on this site,I'm the first to admit it.

 

I'm the same man, when im wrong ill be the first to say, and when im not sure of one of my theories or ideas i'll indicate so. But now my interest is piqed. Time to apply the scientific method to this problem and see whats up.


LOL, I envy y'all in the summer though. Nice and sunny down here in tx today.

Now for the update: No results yet, my truck wouldnt warm to operating temp on the short trip (3-4miles) to taco bell. It's about 70 out today, so its not like its too cold.

Seemed to just hang at around 155-160 (even though it has a brand new 195 stat that i tested). Fixin to take a 1 hour drive though, and deal with houston traffic (ugh) hopefully that'll get it to closed loop where I can give some definitive evidence.

EDIT: just checked the weather... it's 75, should be plenty to get up to temp..... Off to errands.

 

I was just looking for discussion, not trying to get you to say you were wrong. In the end, I learned something today, which is good enough for me

 

Subscribed. Have the same code on my 05 grand caravan 3.8 ltr.

Someone mentioned gutting the Cat and doing something with the Plenum? What/where is the plenum and what do you do to it?

 

Groan. I never thought id be wanting to see a CEL. Still hasnt thrown anything, possibly due to how short my exhaust is.

My theory is that my exhaust is so short with so little backpressure that the rear o2 isnt allowed time to get an accurate reading, hence it may likely never throw a code. Also, my truck seems to be sitting at 165-170 regardless of the horrible traffic I encountered. The stat I put in was 195, but had a larger opening than the stat i pulled out, so it is more efficient at cooling.

Here's some pics of my set up, with/without non-foulers:
the silver pipe i have clamped on there is a turndown, so it ends about 6 inches after the o2

 

To the op: 7/10 times your problem (po420) is a clogged cat, or one that is no longer cleaning the way it should. A clogged cat is usually caused by a blown plenum gasket, which allows oil into the combustion chamber and produces a sh!tton of hydrocarbons which quickly coat the catalyst medium. Do a search here for plenum for more info. The other 3 times it is the rear o2 going bad and lying to the pcm.

To Dank5:I am unsure if your engine even has a plenum gasket, so that's out (however, there are other ways for oil to find it's way into the combustion chamber).

Either your cat is clogged (oil in the CC is #1 cause), going bad (from age), or your rear o2 is going out.

To both of you: Best way to rule out the cat is to take it to a muffler shop and have it pressure tested.

If it's not the cat its the rear (or in very very rare cases, .001% of the time, the front) o2 sensor.

Only reason i add the front to the list is that the rear o2 compares data to the front o2 to see how the cat is doing. If the front is wrongly reporting that oxygen concentration in the exhaust is x and the rear reads close to x it will throw the code.

Usually you would have issues with the engine running rough/misfiring if the front o2 was to blame, because the a/f ratio is largely dependent on data from it.

Good Luck to you both, Keep us updated