Not f#$%&ing happy with my t4rn!!!!

The MAF has something to do with it. Otherwise it wouldn't be in the FSM as one of the check list items for the P0420 code.
 
I had the same issue with my 2000. I started out with New Wires, Plugs, Fuel Filter, Front/Rear Sensors (Bosch... because they were less than Denso).

P0420 came back on... I couldn't make it go away. I did some research and everyone said to stay clear of Bosch sensors. I picked up new sensors (Denso) and never saw the P0420 again.

I also found this as a good resource on what causes the failure. May give you some ideas.

http://www.all-catalytic-converters.com/techtip3.html
 
99Yotarunner said:
was your 2000 cali emissions???? im just stummped and unsure what to do
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Yes... 2000 Cali Emissions. The custom exhaust shop where bring my vehicles (note: i still had stock exhaust) noticed that the gaskets between the flanges had deteriorated as well and flanges were separating (i.e.- not a good seal). They cut out all of the flanges and welded everything back in place. While they had the CATS out they shook them around a few times... they told me they were listening for damage but didn't hear anything.

Since they could not find anything wrong with the CAT visually/audibly, they did not want me to just swap out the CATs. It was time for new wires/plugs and a few other things.

If you lose power when the vehicle warms up or when do a hard acceralation, it may be clogged (or has melted).

Good Luck!
 
99Yotarunner said:
any one have any ideas??? wil the urd or o2 sim work with cali emissions....or what about aftermarket cali cats? im gogin to try the spark plug non foulers trick first since its cheap.......any other ideas
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Yes, it works with CA Emisssions rigs. I have one on my 00' as I was getting the same code. I haven't had a P0420 since.
 
99Yotarunner said:
my mass air is only year old and that has nothing to do with po420 code, and i dont wanna just start buying o2 sensors esp after i just spent almost 300 bucks on both front and rear o2's, i wanna know who is running the urd sim with cali emissions to know if they work.... the guy said it will work but really wana know befor i buy one.......thanks
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Not true.

And, especially since you are running a K&N filter. The K&N needs to be oiled, and that oil will coat the MAF sensor and allow it to get a bunch of dirt/grime on it. This will also trigger a code. Pull the two screws on the MAF, pull it and use some Mass Air Flaw Cleaner to clean it. Seriously, its a common problem with cold air intakes.
 
Yeah i have a dry style filter on it, but il still try cleaning it for a piece of mind. I still dont really understand how that will throw a po420 code tho, i have replaced that sensor about a year ago and the code was comp diff code, and i had horrible throttle response..... I'm ordering the urd sim and going to get ride of both cats and install one high flow cat, glad to here that the urd sim works for everyone. im sure getting rid of the to cats and going to 1 high flow will def help with power and gas mileage.
 
99Yotarunner said:
Yeah i have a dry style filter on it, but il still try cleaning it for a piece of mind. I still dont really understand how that will throw a po420 code tho, i have replaced that sensor about a year ago and the code was comp diff code, and i had horrible throttle response..... I'm ordering the urd sim and going to get ride of both cats and install one high flow cat, glad to here that the urd sim works for everyone. im sure getting rid of the to cats and going to 1 high flow will def help with power and gas mileage.
Click to expand...

Too much air flow or not sensing the correct airflow will set off a rich/lean condition. The O2s will sense this and will either throw a P0171/2 or a P0420 code.

I am not saying this is the reason for your issue, but is a possible reason. FWIW, my cold air intake will throw a P171 code when the MAF gets dirty. I clean it, and am usually good for 3K-4K miles. If I wheel or camp more, the dust will make it come back faster.

I also switched from a dual cat system to a single cat system when I did my SAS, but still got the P0420 code as well. It was there before and after the swap. So, I ordered the Sim unit from URD. Been fine since.

Most OBD-II systems are designed to let you know when the cat is going out. Most will sense this when the cat drops below 95% efficiency. Its still doing its job, but not up to CA specs which is stupid IMO. So, the Sim unit just lets it know its still okay, which it likely is.
 
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Has anyone suggested he try Denso brand sensors? Seems like a no brainer to me.

99Yotarunner: Try Denso brand sensors. Half of the responses you got here said to do the same. I would see if you can get a refund for the Bosch sensors too. You may have to go directly through Bosch, but for a few hundred $$ it would be worth it. Bosch = :redbrick: Denso = :boink:
 
Man I know you don't want to hear this but you probably need to replace the bosch sensors with the Denso ones. Get the part number from URD and then look them up on amazon cause they are a lot cheaper on there. When my P0420 came on it was because of the exhaust gasket by the cat had deteriorated. Have you had someone check your exhaust system for leaks? I would start there if I were you. Good luck man
 
I have checked the exhaust there are no leaks any where, im going to just order the urd sim and install one high flow cat. i have been wanting to do this but did not know about the urd sim untill few days ago..... if i get a po420 code after the sim and ne cat is on il order 2 new denso's but im sure that the sim will make every ting work fine. i will also clean the mass air as i have not cleaned it at alll since i instaled it a year ago or longer

thanks every one for the help
 
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