GEN 2.5 / Rear Catalytic Converter ?'s / MR385644

mk75

Adventurer
Hello All ,

I am in desperate need of a new rear catalytic converter Mitsubishi part number ( MR385644). I have called around to all the usual local suspects, dealers , Mitsubishi focused parts houses and no luck and no Japan support. The local muffler shop can get me left and right catalytic converter but not the rear. I can get a Walker rear catalytic converter welded on the rear but to be honest would prefer to have everthing bolted. So I had a few questions and hope to see if any of you know the answers. FYI this is a California emissions 1999 Montero. Can anyone point me in the right direction?

1. Does anyone know where to source a new rear catalytic converter MR385644 ?

2. Could I convert this California Montero to a non California model in terms of emissions from the manifolds back ? Wondering if I did so if I would have have permanent CEL on the dash or need a computer from a non California Montero?

3. Would an early Gen 3 rear cat work for a Gen 2.5 ? GEN 2.5 # (MR385644) / GEN3 # ( MR514860)

4.Are there better solutions or companies out there than Walker for a weld on option?

Thanks ,
MK-75
 
Did anyone sort out a solve for this? My CEL came on and OBD is pointing to a bad cat on bank 2. It is a CA truck so I assume this is the cat up near the manifold on passenger side. It looks a bit tough to get to and I can't seem to find a source online that still carries them. I've seen some youtube vids where people cleaned their catalytic converters and reinstalled which would buy me some time until I can get to my valve stem seals, assuming this is a major contributor. Could I convert to federal? Again, would I then just end up with a constant CEL as the 'leftover' O2 sensors wouldn't be reading correctly/unplugged? Thanks in advance. (and I did do a pretty extensive search but didn't find a solid solution).
 
My truck is registered in AZ but I live mostly in CA and do my emissions in CA and then mail the forms to AZ DMV when I'm not in AZ when emissions are up..
 

Salonika

Monterror Pilot
Do you have history on your current o2 sensors? How many miles are on them? Without that info, you are stuck not knowing if the sensors are lying to you or if the cat is really fried. I cut a o2 harness out of a donor a while back to make a set of connectors so I can reverse the left and right sides, that way you can at least see if the problem follows the sensors or not. My cats had 180k on them when i did a rebuild, I put in new sensors and haven’t had any issues with my old cats. I’m at 215k now. Unless you are mega burning oil, I’d blame the sensors first. Your computer uses the o2 data to adjust the a/f ratio so I wouldn’t try and modify the system esp. if you are required to pass emissions testing.
 
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montero.life

New member
Did anyone sort out a solve for this? My CEL came on and OBD is pointing to a bad cat on bank 2. It is a CA truck so I assume this is the cat up near the manifold on passenger side. It looks a bit tough to get to and I can't seem to find a source online that still carries them. I've seen some youtube vids where people cleaned their catalytic converters and reinstalled which would buy me some time until I can get to my valve stem seals, assuming this is a major contributor. Could I convert to federal? Again, would I then just end up with a constant CEL as the 'leftover' O2 sensors wouldn't be reading correctly/unplugged? Thanks in advance. (and I did do a pretty extensive search but didn't find a solid solution).

I am in the same boat. I live in New England but have a 1999 California Monty. CEL says I need to replace the passenger's side cat. I have looked everywhere and even called several California auto supply shops to see if they have one stock. No luck. My local muffler shop said that they can put in a non-California compliant cat but no guarantees the light will stay off. I am hesitant to do it because it is a $400 job (parts & labor). I might just try one of those cat cleaners first and cross my fingers that I pass this December.
 

evomaki

Observer
Have you all heard of the Dorman Spark Plug Anti Fouler (PN 42002)? You can search on the internet for its "alternative" uses, which can be pretty handy in some situations such as this. Obviously has to physically fit. Don't know if this solves for a bad O2 sensor, but can keep a good one from fouling. Also, I have no experience with CA or MA emissions. They might be a pretty rabid bunch from what I hear, so caution is the operative word.
 
Do you have history on your current o2 sensors? How many miles are on them? Without that info, you are stuck not knowing if the sensors are lying to you or if the cat is really fried. I cut a o2 harness out of a donor a while back to make a set of connectors so I can reverse the left and right sides, that way you can at least see if the problem follows the sensors or not. My cats had 180k on them when i did a rebuild, I put in new sensors and haven’t had any issues with my old cats. I’m at 215k now. Unless you are mega burning oil, I’d blame the sensors first. Your computer uses the o2 data to adjust the a/f ratio so I wouldn’t try and modify the system esp. if you are required to pass emissions testing.
Point taken. I don't have any history on the sensors themselves and the truck has 156k miles. It does burn some oil but not horribly and has passed emissions in the past without issue. When you say you did a rebuild, are you referring to the cats themselves? How'd you go about this? The vast majority of the posts I've read stated that the cat was the issue vs the sensors but I do like the idea of swapping them to see if the OBD code follows the sensors.. Anyone every clean a cat in laundry detergent? I've seen this posted a few times. Didn't know if it was just snake oil.. I'll probably try the anti-fouler trick just to get through upcoming emissions and then try to sort it properly.
 

plh

Explorer
I replaced the 4 o2 sensors in my '05 a little more than 4 years ago due to a cat not ready code, that worked for 8 months. At that point I did the non-fouler trick on the 2 post cat O2's and cleared the code. Its been clean of codes now for over 3.5 years (est 50k miles) and 2 emissions checks.
 

montero.life

New member
I replaced the 4 o2 sensors in my '05 a little more than 4 years ago due to a cat not ready code, that worked for 8 months. At that point I did the non-fouler trick on the 2 post cat O2's and cleared the code. Its been clean of codes now for over 3.5 years (est 50k miles) and 2 emissions checks.
This is the first time I hear of the non-fouler trick. It is worth a try since they do not cost too much.

PLH, do you remember the size or part number of the fouler you used? I looked up on Amazon the Dorman Spark Plug Anti Fouler (PN 42002) evomaki recommended but it says that it is not compatible with my vehicle. Thanks!
 

plh

Explorer
This is the first time I hear of the non-fouler trick. It is worth a try since they do not cost too much.

PLH, do you remember the size or part number of the fouler you used? I looked up on Amazon the Dorman Spark Plug Anti Fouler (PN 42002) evomaki recommended but it says that it is not compatible with my vehicle. Thanks!

I used 42009
 

Salonika

Monterror Pilot
Point taken. I don't have any history on the sensors themselves and the truck has 156k miles. It does burn some oil but not horribly and has passed emissions in the past without issue. When you say you did a rebuild, are you referring to the cats themselves? How'd you go about this? The vast majority of the posts I've read stated that the cat was the issue vs the sensors but I do like the idea of swapping them to see if the OBD code follows the sensors.. Anyone every clean a cat in laundry detergent? I've seen this posted a few times. Didn't know if it was just snake oil.. I'll probably try the anti-fouler trick just to get through upcoming emissions and then try to sort it properly.
Engine rebuild.
 

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