p0420 code 2011 chevy camaro v6 ls model - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

tscamaro · 06-04-2019, 09:39 PM

so i know i posted another previous thread and im sure it was a bit hard to understand, i have a issue with the p0420 code continuing to come back...the thing is i replaced the cat on bank 1 as well as upstream and downstream. but the code keeps coming back cant get rid of it. anyone else have this issue and what did you do?

ChibiBlackSheep · 06-05-2019, 08:13 AM

What did you replace the catalytic with?

Was it a full OEM cat? Or was it an aftermarket one? Sometimes the aftermarket cat isn't as efficient and will still trip the code. In that case you might need to space the oxygen sensor, or tune out the p0420 code.

LuSINda · 06-05-2019, 01:34 PM

Check your fuses and make sure the wiring isn't chaffed.

tscamaro · 06-05-2019, 01:40 PM

it was a aftermarket high flow cat and i replaced the up and downstream sensors and i run 91 octane what fuse would i look for?

ChibiBlackSheep · 06-05-2019, 01:45 PM

Quote:

Originally Posted by tscamaro

it was a aftermarket high flow cat

This is most likely the issue. They allow readings that are different than the car is programmed for. Your car will keep thinking something is wrong.

You can either space the oxygen sensor, or tune it out. (or throw away a lot of money and put on an OEM cat)

tscamaro · 06-05-2019, 01:50 PM

so im wondering if i need to take it to the dealer or a shop, not sure how id tune it out ive never had this issue, and it seems to me the car is not setting the drive cycle for the ev as well as not getting the right fuel mileage. whats even stranger is not to lomg ago prolly around 2 weeks maybe 3 i got thw car smogged and it passed after i replaced the cat, a buddy hooked it up to his snap on diag machine to make sure the light was green after driving it and it was. the only thing that wasnt and hasnt been is the ev light flashing

tscamaro · 06-05-2019, 01:51 PM

would i space the up or downstream sensor? weird how its only on bank 1.

tscamaro · 06-05-2019, 01:57 PM

thank you for your advice. @lusinda what would i do if they are chafed...i beleive thats if they are crossed or broken right?

ChibiBlackSheep · 06-05-2019, 02:18 PM

Quote:

Originally Posted by tscamaro

whats even stranger is not to lomg ago prolly around 2 weeks maybe 3 i got thw car smogged and it passed after i replaced the cat, a buddy hooked it up to his snap on diag machine to make sure the light was green after driving it and it was. the only thing that wasnt and hasnt been is the ev light flashing

The aftermarket cat is working fine, just the readings to the oxygen sensor are different than stock, so the car throws the CEL.

Quote:

Originally Posted by tscamaro

would i space the up or downstream sensor? weird how its only on bank 1.

You space the oxygen sensor after the cat. Downstream.

I'm also concerned with how you had to replace the cat on such a new car. Typically something like that would be warrantied higher and longer. If something was truly wrong with the stock cat, if you were under 80,000 miles (I think), it should have been a warranty replacement.

I'm concerned you might be running rich to start with.

tscamaro · 06-05-2019, 08:17 PM

well heres something interesting, i just got dome driving the car i went into the store to buy something came out and poof check engine light suddenly gone...got home and scanned it with a standard obd2 reader and instead of there beimg 3 codes which read p0420 freezeframe, p0420 pending, p0000 code...now there is a p0420 freeze frame but no light....now the rich part i thought the same thing but im not to sute as to why i would be or what to do..the reason i had replaced the cat is because i didnt know my upstream sensor was bad until i got some good reading so what im thinkimg is both sensors were bad on that bank and i screwed myself over and i didnt know.

ChibiBlackSheep · 06-06-2019, 08:14 AM

Pull a plug or 3 and check to see how they look. That should tell you if you are running rich or not (or check your LTFTs while driving if you have the capability).

Hopefully you are good for now, I would clear it and see if it comes back. If it does, GM won't help you tune it, but you should be able to buy an o2 extender

LuSINda · 06-06-2019, 11:19 AM

Quote:

Originally Posted by tscamaro

thank you for your advice. @lusinda what would i do if they are chafed...i beleive thats if they are crossed or broken right?

You would need to repair or replace the wire. Check all your wiring and connector looking for bare/pinched wires and fix as needed.

The sensors run on individual circuits is why one can go bad and the others work.

The pre-catalytic converters are protected by Fuse #7. The post-catalytic converters are protected by Fuse #8.

tscamaro · 06-06-2019, 12:13 PM

the engine light automatically went off yesterday for the first time in a month since all this has been done. when i purchased the car i had to 1. replace the spark plug tube seals due to the fact that they had oil on the plugs so i did the whole gasket set. than i replaced the plugs and checked them not to long ago and they are a bit carbony. than i did a coolant change on it as well as the 02 sensors. the cat may have went bad due to however long the last owner drove with oil on cylinder number 2 and 4?

tscamaro · 06-06-2019, 12:17 PM

i was going to post a pic of the old plug but not sure how to. by the way the camaro has 116,000 miles on it. and i also know theres a small leak coming from the air cleaner box because one of the clips are broken. but im having a hard time finding a cold air or just the part thats broke

06-04-2019, 09:39 PM	#1
tscamaro Drives: chevrolet Join Date: Apr 2019 Location: 92307 Posts: 14	p0420 code 2011 chevy camaro v6 ls model so i know i posted another previous thread and im sure it was a bit hard to understand, i have a issue with the p0420 code continuing to come back...the thing is i replaced the cat on bank 1 as well as upstream and downstream. but the code keeps coming back cant get rid of it. anyone else have this issue and what did you do?

06-05-2019, 08:13 AM	#2
ChibiBlackSheep Drives: 2012 2SS/RS, 1968 SS Join Date: Feb 2012 Location: Southeast, PA Posts: 2,099	What did you replace the catalytic with? Was it a full OEM cat? Or was it an aftermarket one? Sometimes the aftermarket cat isn't as efficient and will still trip the code. In that case you might need to space the oxygen sensor, or tune out the p0420 code. __________________ LS3 Crate Engine Swap \| CSP Custom Cam 232/240 .615/.615 113 +3 \| Stainless Power LT Headers \| Z28 Intake \| Borla S-Type Exhaust \| FTI Triple-Disc Billet 3200 Stall 2012 Camaro 2SS/RS \| 1968 Camaro SS \| 2020 Cadillac CT5 Premium Luxury \| 2021 Spark LS

06-05-2019, 01:34 PM	#3
LuSINda Drives: 2010 2SS/RS Join Date: Jun 2015 Location: Washington Posts: 94 View My Garage	Check your fuses and make sure the wiring isn't chaffed. __________________ Lusinda 2010 2SS/RS

06-06-2019, 08:14 AM	#11
ChibiBlackSheep Drives: 2012 2SS/RS, 1968 SS Join Date: Feb 2012 Location: Southeast, PA Posts: 2,099	Pull a plug or 3 and check to see how they look. That should tell you if you are running rich or not (or check your LTFTs while driving if you have the capability). Hopefully you are good for now, I would clear it and see if it comes back. If it does, GM won't help you tune it, but you should be able to buy an o2 extender __________________ LS3 Crate Engine Swap \| CSP Custom Cam 232/240 .615/.615 113 +3 \| Stainless Power LT Headers \| Z28 Intake \| Borla S-Type Exhaust \| FTI Triple-Disc Billet 3200 Stall 2012 Camaro 2SS/RS \| 1968 Camaro SS \| 2020 Cadillac CT5 Premium Luxury \| 2021 Spark LS

06-05-2019, 01:40 PM	#4
tscamaro Drives: chevrolet Join Date: Apr 2019 Location: 92307 Posts: 14	it was a aftermarket high flow cat and i replaced the up and downstream sensors and i run 91 octane what fuse would i look for?

06-05-2019, 01:50 PM	#6
tscamaro Drives: chevrolet Join Date: Apr 2019 Location: 92307 Posts: 14	so im wondering if i need to take it to the dealer or a shop, not sure how id tune it out ive never had this issue, and it seems to me the car is not setting the drive cycle for the ev as well as not getting the right fuel mileage. whats even stranger is not to lomg ago prolly around 2 weeks maybe 3 i got thw car smogged and it passed after i replaced the cat, a buddy hooked it up to his snap on diag machine to make sure the light was green after driving it and it was. the only thing that wasnt and hasnt been is the ev light flashing

06-05-2019, 01:51 PM	#7
tscamaro Drives: chevrolet Join Date: Apr 2019 Location: 92307 Posts: 14	would i space the up or downstream sensor? weird how its only on bank 1.

06-05-2019, 01:57 PM	#8
tscamaro Drives: chevrolet Join Date: Apr 2019 Location: 92307 Posts: 14	thank you for your advice. @lusinda what would i do if they are chafed...i beleive thats if they are crossed or broken right?

06-05-2019, 08:17 PM	#10
tscamaro Drives: chevrolet Join Date: Apr 2019 Location: 92307 Posts: 14	well heres something interesting, i just got dome driving the car i went into the store to buy something came out and poof check engine light suddenly gone...got home and scanned it with a standard obd2 reader and instead of there beimg 3 codes which read p0420 freezeframe, p0420 pending, p0000 code...now there is a p0420 freeze frame but no light....now the rich part i thought the same thing but im not to sute as to why i would be or what to do..the reason i had replaced the cat is because i didnt know my upstream sensor was bad until i got some good reading so what im thinkimg is both sensors were bad on that bank and i screwed myself over and i didnt know.

06-06-2019, 12:13 PM	#13
tscamaro Drives: chevrolet Join Date: Apr 2019 Location: 92307 Posts: 14	the engine light automatically went off yesterday for the first time in a month since all this has been done. when i purchased the car i had to 1. replace the spark plug tube seals due to the fact that they had oil on the plugs so i did the whole gasket set. than i replaced the plugs and checked them not to long ago and they are a bit carbony. than i did a coolant change on it as well as the 02 sensors. the cat may have went bad due to however long the last owner drove with oil on cylinder number 2 and 4?

06-06-2019, 12:17 PM	#14
tscamaro Drives: chevrolet Join Date: Apr 2019 Location: 92307 Posts: 14	i was going to post a pic of the old plug but not sure how to. by the way the camaro has 116,000 miles on it. and i also know theres a small leak coming from the air cleaner box because one of the clips are broken. but im having a hard time finding a cold air or just the part thats broke