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Discussion summary
YOUR RESEARCHCEL with code P0420 after muffler bypass
Leading reported evidence
Run bypass pipes
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
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1
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Performed · outcome unconfirmed
Manil, I ran bypass pipes for several years with not a single issue.
Leading evidence: 'Run bypass pipes' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check any exahust leak' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed · Original poster
I will either get used cats or go with the fabspeed x pipes.
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Suggestion
I would check for any exahust leak on bank 1, especially where the cat mates to the straight pipe.
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Suggestion · Original poster
Anyone have any luck in a dealer replacing cats just outside the 8/80 warranty?
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Rennlist: 1 discussions
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I had muffler bypass pipes put in a month ago. Drove it for around 500 miles since including a DE at VIR.
While riding dirty this friday evening the car threw a check engine light. Autozone code reader says P0420 catalyst system efficiency below threshold bank 1.
Car has only 25k miles on it. I am pretty sure its related to the muffler bypass mod I did. Did I blow and O2 sensor? What fix am I looking at? Am I hurting it by still driving?
Help!!
Manil, I ran bypass pipes for several years with not a single issue. My guess would be that it is NOT a result of slapping on the bypass pipes. And no, you are not hurting it by driving it.
And what is "driving dirty"? Were you getting freaky in the car?
Get your butt down to Apex for coffee tomorrow and see if Scott has his Durametric fired up yet. If so, get a better read, clear the code, go on a drive and see if it comes back.
IF
you toasted your 02 sensor, I can't see how its related to the BPPs. Now, having said that,
flat out
Blue Group driving at the track.....
Any other symptoms? Bad idle, stumbling, loss of power, etc.?
Pull the negative batt cable for a few minutes, drive for a few days, and see if it come back. Have you done anything else different recently?
I would check for any exahust leak on bank 1, especially where the cat mates to the straight pipe. It's unlikely your cat has failed in such low mileage.
@ Dell... Lol...No freakiness in the car(I wish). Just driving around on a fri evening harassing the good ppl of Winston-Salem with my loud car!!
@Scott .. Did not do much after the DE. The car has been sitting around mostly. Got my ignition switch issue taken care of but that's about it. Car rides fine.. Feel no difference. Will try the (-)ve battery lead removal tomorrow and report back.
@Asahi .. Will check to see if the clamp is loose to the straight pipe. It was sort of a hack job anyways at the local muffler shop.
What is bank 1 anyways? Is it left or the right side?
I think I am just out of the federal 8/80k warranty on cats. Although I have a top of the line exclusionary extended warranty I doubt if cats are covered.
Any chance that the rattle from muff bypass shook something in the cats? The car is an 02 but only has 26k miles on it.
If not covered, I may have to get used ones or fancier ones from fabspeed. Any recommendations?
Am gonna clear code today to see if the error comes back.
Scott....I looked at your pics of the X-pipes install. I think you need mufflers to go along with those pipes. I do have my Fabspeed mufflers that I took off but was planning to be unmuffled for a while. I am just in love with that sound track!!
Anyone have any luck in a dealer replacing cats just outside the 8/80 warranty?
No, it should work; the xpipe section simply replaces the cats; the exit piping is the same (
link
) as the stock cat section since it is designed to work with the stock mufflers; so in your case, instead of the flow going to the mufflers, it would go to the bypass pipes.
The setup, even with my stock mufflers sounded fantastic, so even if you wanted to use your FB mufflers, it also should sound great.
I wouldn't hold my breath for cat replacement by the dealer, especially when they see your bypass pipes, even though they likely have no true effect on the cats.
Take it by the dealer; the worse they can say is No, then order the cat section from FB or FVD.
put it back to stock and then take it to the dealer. if it was still in warranty I would keep the parts but since you're looking for a favor, its best to be stock...
+1 again, if you are planning to take it to a dealer.... DO NOT RESET THE CEL! They wont even look at it if it doesnt have a code.
If your are going the X-pipe route, here is my install... Its a FVD setup, essentially the same as fabspeed.
https://rennlist.com/forums/996-foru...s-and-vid.html
Disconnecting battery and clearing code helped. Check engine light is not back....drove it for around 15 miles without issue.
I am sure it will be back again soon but am good for now.
Thx all
Also took the time to read the warranty booklet. The emissions warranty is for 7 years so i am 2+ years out of warranty.
Also my extended warranty specifically does not cover the cats.
If it comes back... I will either get used cats or go with the fabspeed x pipes.
desidon
i've had Mercedes Benz take care of a cat for me 2 years after before so don't rule that option out. always give it a shot. it never hurts. Also, make sure you drive it a long time. I've found that p0420 codes are a PITA and sometimes codes won't come on for 100 miles!
