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View Full Version : CEL P0420: Catalyst Efficiency Below Threshold - Help


KevinEP3
04-01-2011, 02:50 PM
Car threw CEL P0420 need suggestions. I had the CEL cleared and it came back on after about 20 miles. I've been looking online so far I found a direct fit catalytic converter on eBay shipped from Canada for $185, $250 (MAC - Brand) shipped from New York, and $275 + tax from a local import parts dealer. Is there a dif between the ones from Canada vs. USA? Also, I posted a WTB thread for a used one but later saw that buying a used one is illegal. Is this true? Anybody over recycle their old one?
tunner2307
04-01-2011, 03:44 PM
Car threw CEL P0420 need suggestions. I had the CEL cleared and it came back on after about 20 miles. I've been looking online so far I found a direct fit catalytic converter on eBay shipped from Canada for $185, $250 (MAC - Brand) shipped from New York, and $275 + tax from a local import parts dealer. Is there a dif between the ones from Canada vs. USA? Also, I posted a WTB thread for a used one but later saw that buying a used one is illegal. Is this true? Anybody over recycle their old one?

I had the same problem, change your secondary o2 sensor, I bought the denso one from autozone and there is no cel for over 2000 miles
KevinEP3
04-01-2011, 04:37 PM
I thought about that but I red this thread and it says it won't work. http://www.ephatch.com/forum/showthread.php?57079-P0420&highlight=p0420
tunner2307
04-01-2011, 04:52 PM
I thought about that but I red this thread and it says it won't work. http://www.ephatch.com/forum/showthread.php?57079-P0420&highlight=p0420

Yeah I was confused too. I red that post when I had the cel on and I ended up buying new cat, but it didn't help. Then I changed a secondary 02 sensor and cel didn't show up again.
KevinEP3
04-01-2011, 05:04 PM
well I might try this then. I've been having CEL issues for 2 yrs. last yr it was the primary and now its this. So if the secondary fix dont work then new cat it is and hopefully I wont have to worry about any more emission problems.
tunner2307
04-01-2011, 05:59 PM
well I might try this then. I've been having CEL issues for 2 yrs. last yr it was the primary and now its this. So if the secondary fix dont work then new cat it is and hopefully I wont have to worry about any more emission problems.

Yes you right Good Luck
KevinEP3
04-02-2011, 06:54 PM
Good for another year. Replaced the secondary O2 sensor with the Denso and went through the drive cycle only. So far so good. So for anyone that gets this code I would try the $65 sensor before paying $300 - $700 for a catalytic converter. If the sensor doesnt work hell your only out 65 vs 3-700.

Now I have more $$ for tires!