P0420 code is back
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Joined: 06-21-16
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From: Sheboygan Wisconsin
P0420 code is back
Hi Guys,
I have the annoying p0420 code again. I checked the live stream data and noticed the downstream O2 sensor fluctuates like the upstream (although the numbers aren't exactly the same. My MPG is around 22 (mixed city and highway). One thing I've noticed is the inside of the exhaust manifold is real sooty (dry, not oily) Not sure if the catalytic converter is going bad? It's a ZZP downpipe with a high flow cat. I was thinking about replacing it with a Magnaflow cat. Currently I have the downpipe off because I had to get at the caged nut which broke while pulling the control arm off. From the entrance, the honeycomb doesn't look bad, and no rattles. The car starts fine and accelerates...OK...but not like it used to. What else to check for?
Thanks
I have the annoying p0420 code again. I checked the live stream data and noticed the downstream O2 sensor fluctuates like the upstream (although the numbers aren't exactly the same. My MPG is around 22 (mixed city and highway). One thing I've noticed is the inside of the exhaust manifold is real sooty (dry, not oily) Not sure if the catalytic converter is going bad? It's a ZZP downpipe with a high flow cat. I was thinking about replacing it with a Magnaflow cat. Currently I have the downpipe off because I had to get at the caged nut which broke while pulling the control arm off. From the entrance, the honeycomb doesn't look bad, and no rattles. The car starts fine and accelerates...OK...but not like it used to. What else to check for?
Thanks
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