Dtc code p0420 & p0430

I got my LT and catted H pipe installed last weekend. They sent the wrong 02 extensions. Never got this code while driving all last week without the extensions. Got the right ones installed last night. Didn't see a code then or this morning. After driving for a bit after work the code popped up. The code says Catalyst system efficiency below threshold. Would that be cause of some bad 02 sensors? Or actual bad cats? (Brand new catted h pipe). Or would the code just be there cause I have different cats now.

The main culprit is probably the extensions. There is too much resistance thus making it throw codes. The best thing to do is drill new o2 bungs near the stock locations so that you will not need to rely on extensions (which rarely work right). If I were you I would also send datalogs to my tuner after everything has been installed as fueling will change significantly after removing the cats. That will ensure you're dialed in and safe.

Thanks! I'll look into drilling new holes and will definitely datalog. The LTs are awesome so I hope it's just the extension

SquillyP said:

Thanks! I'll look into drilling new holes and will definitely datalog. The LTs are awesome so I hope it's just the extension

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Keep us posted with the results!