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P0420
Sent to Car Experts April 13 09:23 PM

I change cat 3 weeks ago and now iam having this code P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
What can i do. (probably this cat is aftermaket, iboght it online Direct Fit Cat)

 

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2003 Chevrolet Impala 3.4

Customer (name blocked for privacy)
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April 13 9:34 PM (10 minutes and 55 seconds later)
         
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April 14 10:55 PM (1 day and 1 hour later)
         
Relist: I still need help.
What you mean? Its new cat, maybe just after market one. Maybe i can change sensors or put simulator or something.
Answer
April 14 11:30 PM (34 minutes and 29 seconds later)
         
ACCEPTEDCheck Mark

what you can do is take this to a shop that has a diagnostic computer. with this they can watch the o2 sensors to see if they are fluctuating as they should. the code you are getting is that the catalytic converter is Below Threshold.

this means that the catalytic converter is damaged inside like one of the fins is ether bent from the high heat or one or more fins has broken off. if this is the case this will not slow the exhaust to remove the unburnt gases that is the job of the catalytic converter.

aftermarket parts are cheaper and thus not up to OEM standards. you get what you pay for with aftermarket parts




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Thanks
David
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