P0420: Do I need a new catalytic converter?

[AaronPaul]

In my 9 years experience working on cars and trucks, I have never seen a p0420 or p0430 be caused by anything but a cat.

Mind if I ask you about this?

 

[j33pster87]

Has the vehicle been driven hard since the other issues? If not, carbon and other deposits can build up on the catalyst and reduce its efficiency. If it hasn't been run hard, a long Italian tuneup might be a good way to try and clean it out. The idea would be to get the catalytic converters as hot as possible. If you can find a freeway that allows 75+ and do a lot of hard acceleration or fast hill climbs, that should burn up any deposits.

If that doesn't do anything, it may be worth replacing the catalytic converters. I replaced mine with a bolt in Magnaflow unit. It wasn't cheap but it fit perfectly and has given me zero issues.

Does your direct fit magnaflow catalytic converters have any heat shield. I bought some and was told they don't need heat shield there built to be without it. Just has me worried for everything that sits around them once they heat up

 

[Steel City 06]

Does your direct fit magnaflow catalytic converters have any heat shield. I bought some and was told they don't need heat shield there built to be without it. Just has me worried for everything that sits around them once they heat up

The 3rd cat has one. The two pre-cats do not, but it has never been an issue for me. I think insulating the exhaust header would have a bigger impact than the catalytic converters.

 

[jcw]

After getting a p1196 (and replacing the corresponding o2 sensor) and a repeated P0420 code, I decided to pull the cats off for further inspection. The front side on all was pristine. Unfortunately while having them off and shaking, I discovered a rattle inside. Upon further inspection with a scope camera I noticed the honeycomb on the one precut is totally gutted on the back side and I was able to pull a large amount of the cat material out.

Am I right in assuming that even if I clean it out fully, it still won't be functional?
If so, can anyone recommend a "budget" new precat/cat system (Mandrel bent) that will bolt right up and is hopefully less than magnaflow's $1400 system ?

 

[MikeE024]

After getting a p1196 (and replacing the corresponding o2 sensor) and a repeated P0420 code, I decided to pull the cats off for further inspection. The front side on all was pristine. Unfortunately while having them off and shaking, I discovered a rattle inside. Upon further inspection with a scope camera I noticed the honeycomb on the one precut is totally gutted on the back side and I was able to pull a large amount of the cat material out.

Am I right in assuming that even if I clean it out fully, it still won't be functional?
If so, can anyone recommend a "budget" new precat/cat system that will bolt right up (hopefully less than magnaflow's $1400 system)?

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Looking them up for your year on Rock auto is a good start. Also cross those parts to Amazon…I saw some precats on sale there once bc they were returned.

 

[jcw]

Looking them up for your year on Rock auto is a good start. Also cross those parts to Amazon…I saw some precats on sale there once bc they were returned.

I looked on rock auto and saw some Davico pre cats and AP/Eastern 3rd cat (not familiar with the brands) for what looks to be a reasonable prices. Hoping for anyone with experience / insight with any of these brands to provide a stamp of approval. Hate to go through the trouble of buying / installing them just to learn they are complete junk

 

[MikeE024]

I looked on rock auto and saw some Davico pre cats and AP/Eastern 3rd cat (not familiar with the brands) for what looks to be a reasonable prices. Hoping for anyone with experience / insight with any of these brands to provide a stamp of approval. Hate to go through the trouble of buying / installing them just to learn they are complete junk

AP / Eastern are well known. I wouldn't hesitate to run them if they are your only affordable option.

I don't know about Davico, but that doesn't mean they aren't as good or better.

The Flowmaster cats that I have aren't anything special and got crazy expensive after the Covid shortage. Magnaflow are even more expensive that FM.

I'll shoot you a PM here in a second.

 

[11_Kiki_11]

Hello folks. I know for a fact that my check engine light is due to bad precats. Unfortunately, my VECI shown below would suggest that I need a CARB converter. While I am inclined to trust Steel City 06 on this matter, I just want to be sure that it is a fact that I will need a CARB version in order to avoid the engine light and other issues from the ECM. I also live in Pittsburgh, PA and thus would absolutely love to pay less than $2221 for this part. The Magnaflow seems like the only sure-quality option out there right now, so I'd love to hear otherwise. Thanks!

Under the hood, there should be a big sticker that has the emissions information. It will either say something like California emissions or federal emissions.

If it has a sticker for California emissions, you will need a catalytic converter compatible with that emissions system. It doesn't necessarily need to be a CA-legal converter, but it does need to be compatible.

Vehicles with CA emissions software have a higher threshold of emissions standards, and require more rare metals in the catalytic converters to achieve the threshold necessary to turn off the CEL. Vehicles with EPA minimum software can get away with heavy metal catalytic converters, which aren't as efficient.

California requires a very specific sizing for catalytic converters, so not only do they need the higher rare metal load, they need to be sized differently than most aftermarket manufacturers do. Vehicles with CA emissions outside of California are not subject to these requirements.

Magnaflow makes all three kinds of catalytic converters. The rare metal converters will work fine in a vehicle that only requires heavy metal converters, but not the other way around. The rare metal converters are more efficient at converting pollutants into inert gases.

 

[macleanflood]

Your PCM doesn't know anything about a sticker.

All it cares about is sensors being in normal operating parameters.

The only reason you need a CARB compliant sticker is to pass an inspection.

-Mac

 

[11_Kiki_11]

Your PCM doesn't know anything about a sticker.

All it cares about is sensors being in normal operating parameters.

The only reason you need a CARB compliant sticker is to pass an inspection.

-Mac

While your logic is sound, this may directly contradict the post that I replied to in this thread. The point being, I have heard both outcomes presented as truths. I am curious if anyone has any actual empircal data, anecdotal or otherwise, involving this situation:

Let's say there was an 04-06 TJ, with a stock CARB setup, that was then fitted with an EPA converter. Since I have heard that the ECM may monitor for different thresholds in each case, would such a scenario present an engine light?

 

[11_Kiki_11]

As an update, I snagged the last Flowmaster Direct Fit (EPA) on Extreme Terrain. Since installing it yesterday, I have not seen any codes. So, at least thus far, it would seem that the ECM is okay with this.