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Old Aug 29, 2018 | 09:00 AM
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Default Trouble code

02 Corvette coupe LS one PO 420 bank one what does this mean does anybody know I'd appreciate any help the car seems to run good
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Old Aug 30, 2018 | 06:34 AM
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P0420 is Cat efficiency below normal on Bank 1...do you have a scan tool that can graph your O2 sensor signals ??...will help immensely in the diagnosis !!
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Old Aug 31, 2018 | 01:56 PM
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Default Trouble code

Originally Posted by rwobs777
P0420 is Cat efficiency below normal on Bank 1...do you have a scan tool that can graph your O2 sensor signals ??...will help immensely in the diagnosis !!
Thanks I'll have to check with my friend I appreciate your help
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Old Aug 31, 2018 | 04:45 PM
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Originally Posted by okgo
Thanks I'll have to check with my friend I appreciate your help
No problem !!...if your post cat O2 sensor waveform looks like the upstream after the cats get hot you have a bad cat...the cat no longer has the ability to store oxygen !!...any questions let me know !!
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Old Sep 2, 2018 | 08:11 PM
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Do you have headers on your car ????? If you have LT headers this is a common issue and most likely will never go away Best way is to have a tuner DELETE all the REAR 02 reporting and codes permanently
PS The front 02's are very important as they take readings ane by those readings the ECM makes adjustmets to your AFR at P/T to achive the STOICH fuel ratio of 14.68-1
HOWEVER the rear 02,s are only there to "report the condition of your CATS" and have no affect on fueling at P/T ( unless the cats are plugged up) Before spending what can be $1000 on new cats I would take your car to your local muffler shop and they have a tool that can measure the restriction in your cats to see if they are plugged If they are --You need new ones---If they are NOT then most likely it is what they call a "fasle code" from lazy rear 02's Then you can either change them or have a tuner delete the cat codes forever !

Last edited by tblu92; Sep 4, 2018 at 04:58 PM.
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Old Sep 2, 2018 | 08:49 PM
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Originally Posted by tblu92
Do you have headers on your cae ????? If you have LT headers this is a common issye and most like;y will never go away Best way is to have a tuner DELETE all the REAR 02 reporting and codes permanently
PS The front 02's are very important as they take readings ane by those readings the ECM makes adjustmets to your AFR at P/T to achive the STOICH fuel ratio of 14.68-1
HOWEVER the rear 02,s are only there to "report the condition of your CATS and have no affect on fueling at P/T ( unless the cats are plugged up) Before spending what can be $1000 on new cats I would take your car to your local muffler shop and they have a tool that can measure the restriction in your cats to see if they are plugged If they are --You need new ones---If they are NOT then most likely it is what they call a "fasle code" from lazy rear 02's Then you can either change them or have a tuner delete the cat codes forever !
Hi !!...there are 2 different CAT issues you can have ...they are either really plugged up (driveability issues for sure...low power) OR the DTC the OP is experiencing...CAT efficiency (cat has problems storing oxygen. The rear O2’s don’t switch like the front ones but are normally steady around stoic (450mV)...mine normally hang around 600 mV !!...one can use an infrared thermometer to read the inlet vs outlet temps but I would much rather use my vacuum/pressure gauge with an O2 sensor adapter !!...now this is all predicated on if we are talking about an OEM exhaust system !!
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