CEL after new exhaust

[OGsohcHondaLOVE]

Mostly feels the same. Nothing has changed as far as wire routing or anything. What fuse would I look fir pertaining to the exhaust system? Maybe the cat was bad but there was enough back pressure from the system before that the sensor could read it. Now it flows faster or something? I had a friend do the system, nit going to bust balls over a catalyst code.

 

[moparman]

An exhaust leak close to the cats could kick a p0420 or 430 code. The leak would cause the downstream o2's to have a different reading than upstream therefore causing the code. Its coming back on every 25-30 miles because the computer is seeing that the cats are up to temp and its going to run the catalyst effciency test for that drive cycle then realise the readings dont match and set the cel

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[OGsohcHondaLOVE]

Maybe I can try to replace the collector gasket to see if that may be the problem? I know my "hemi tick" is a lot louder on the passenger side than the driver and I was wondering if it was more of an exhaust leak than a valvetrain problem.

 

[moparman]

Maybe I can try to replace the collector gasket to see if that may be the problem? I know my "hemi tick" is a lot louder on the passenger side than the driver and I was wondering if it was more of an exhaust leak than a valvetrain problem.

If its louder on the passenger side then thats youre problem. Try replacing the gasket and go from there. Air escaping the exhaust before its read by the o2 sensor can cause a cat code

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[truckin151]

did you have the code before the exhaust went on though? I would seriously call the guy that did it and ask him what he did when welding it up. did he pull everything off from the manifolds back? unbolt the cats from the collectors? if he did not touch that stuff, and the code want there before then it is probably not whats causing the problem, unless he really cranked and pulled on the pipes to line then up and jarred something loose.

 

[OGsohcHondaLOVE]

He did not pull the cats from the manifolds.

 

[man n black]

Hmmm.... Did you rule out O2 sensor yet?

Ch

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[OGsohcHondaLOVE]

I already replaced the downstream so it can't be that. Returned the truck to stock tune so it wasn't that. Can't be an exhaust leak or the upstream sensor would go off too. Right? Is there a possibility that it just flows that much better? Or maybe the way the merge was done on the y?

 

[truckin151]

something about the way the stock piping and new piping look where they are merged doesn't look right to me. the is a possibility your guy pulled on the piping to align it and jarred it loose. check and see if the collectors above the cats are loose. literally climb under and try to move the piping while cool.

 

[OGsohcHondaLOVE]

I will check but since the upstream sensor is right after the collector then the cat and then the downstream sensor I really don't think that is the problem. I will take a look at that though.