My CEL turned on the other night so when I got to work the next day I hooked up the tech 2 and it ended up being a P0420. First I checked to see if the HO2 sensors were working and the were working normally so then I cleared it.

I installed the zzp 3 inch downpipe with high flow cat around 1000 miles ago. Is it possible that the cat is failing already or is it just that our PCM isn't likeing it? I think its more along the lines of, my pcm doesn't like it, but could it be the cat. I would have thought that if it didn't like it it would have come up much sooner, but I could be wrong

I would be ok with just clearing it everytime it comes on, but my problem is my inspection is coming up in October and we have an OBD2 emmisions test so CEL= fail. Even though I do my own inspections there is no way around it. Clearing it is going to reset the rediness monitors and that will fail it too if more then 1 has not cleared. Do I need a pcm reprogram to eliminate the P0420 permanently, or should i email zzp and see what they will do? Thank you for any help

 

Hi LabNjab, Check back on your thread question 2 see what our expert tech member's post/suggest. Also, it never hurts to contact expert people like ZZP for assistance/infor.
Below are a few links you may also want to check out...Good Luck from `Space.
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I have the same setup and your stock o2 sensor is not setup to digest the new flow rate as being in tolerance.

I also had the same problem an installed an o2 emulator from ZZP. No more code and I have been through several inspections so far without a problem.

 

Exactly right.

The new downpipe flows much higher than the stock one, so your PCM thinks something is wrong when nothing is in fact wrong.

You can find someone who tunes 3800 engines and get the P0420 code deleted.
You can buy a canned PCM with the code deleted already.
Or you can try the O2 simulator that ZZP sells. (but if you were going that route, honestly Id just do a PCM for a few bucks more)

 

..BlackSheep `Mike, it's great to have you back & helping your MCF Family 4-Sure : )

+++++Also super to see Moderator Montejass back online...`Todd it is so great to see you online with
your original User Name : ) Welcome back Home : )

 

Thank you everyone. I'll probably get a pcm from zzp unless I can find someone locally to tune it. I read that the o2 emulators don't work on 04's. I was planning on a tuned pcm eventually but looks like I'll get it sooner. I need to get the cooling fans to kick on at 180 so I can get them to delete the code at the same time...is there anything else I should have done to the pcm that would possible give better performance? Right now I just have a 180 t'stat, zzp down pipe and wizaird CAI

 

Just let them know what you have, and stress that you want the Monte Carlo Bin files.

 

Is DHP still pushing a decent software interface? I had not heard of the emulator issues with the 04's, wonder what the difference is between the 03 & 04 sensors?!?!?!

I opted for the simple most cost effective method to kill my O2 issue and went with the emulator; looking back it would have been nice to play around with the software out at the time to manipulate the PCM.


Thanks Space.... I've been poking around my usual MC sites looking for info; the ole Monte is getting up there in miles and starting to have some quirks.

 

3800performance says the o2 emulator will not work on 2004 vehicles. Looks like I'm going to get the custom pcm from zzp. I priced out dyno tuning locally and its at least $500. Now I just need to save up for it. The core charge is the killer, lol. If it wasn't for that I could order it today

 

Also check out overkill PCMs

http://www.getoverkilled.ca/L67CompProg.html

Or drop onto clubgp.com/newforum and see if you can find someone locally that will tune.