P0420 on replaced catalytic converter - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

sstephen17 · 03-06-2023, 06:05 PM

Back in 2019, I had the P0420 code with bank 2 efficiency. Since I'm in California, the emissions warranty is good for 8 years (2014 Camaro LT). I took it to the dealer and they said they had to replace the catalytic converter. Mileage was 47,000 at the time.

In February of 2023, I got the same error code but this time with bank 1 efficiency. Mileage now is 73,000. I've gotten an oil change, cleaned the TB, MAF, and air filter. Manually cleared the code three times but it always comes back with the same code after about 150 miles. My only mods are a catch can and an Airaid modular intake tube.

Took it to a mechanic (non-dealer) and they said I need a new catalytic converter. My question is, does a cat that is replaced by the original warranty get covered or am I out of luck getting it replaced/fixed by the dealerxx?

gtstorey · 03-06-2023, 07:05 PM

Does it not have a separate cat for each bank? Sounds like it probably does based upon the bank 1 and bank 2 description.

KillboyPowerhead · 03-06-2023, 07:10 PM

If it's been longer than 8 years now than I imagine you'd be paying for it.

Quote:

Originally Posted by gtstorey

Does it not have a separate cat for each bank? Sounds like it probably does based upon the bank 1 and bank 2 description.

Yup, two cats on either side.

I got this code after installing the Mace cams. Was worried that the timing was off, but I was also running super rich. After getting the fuel dialed in closer to stoich the code went away. Have you done any scanning to check your long term and short term fuel trims? I imagine this wouldn't be an issue since you're mostly stock, but just a thought.

sstephen17 · 03-06-2023, 08:53 PM

Thanks for the info. I have to do smog next year (did it in 2021) so I'll have to make a decision on paying for a new cat before then or getting a new car, which my wife and I planned to do sometime in 2024.

TommyTheCat · 03-14-2023, 06:10 PM

could also be a defective O2 sensor, pretty strange for your cats to have worn out so much on the same bank again. you ever drive the car with the engine light on for rich codes or misfire codes?

sstephen17 · 03-17-2023, 12:39 PM

Quote:

Originally Posted by TommyTheCat

could also be a defective O2 sensor, pretty strange for your cats to have worn out so much on the same bank again. you ever drive the car with the engine light on for rich codes or misfire codes?

It's actually a different bank. Bank 2 when it got replaced and now I'm getting bank 1. Maybe I should have them replace the O2 sensors?

I do have an Autel OBD2 Scanner MS309. It can get freeze frame data; is there anything I should be looking for other than the P0420 code it gives?

zmotorsports · 03-17-2023, 12:48 PM

Look at your upstream and downstream O2 sensor signals. The upstreams should be switching hi/lo relatively quick and the downstreams should be relatively "lazy", almost non responsive but just floating along and I like to see in the 350mV to around 650mV range.

If the downstreams are switching similar to the upstreams then the catalytic converter is not functioning. I also like to shoot the inlet and the outlet with an IR gun. You want to see the outlet approx. 100 degrees Fahrenheit hotter than the inlet side to determine if the catalytic converter is functioning (lighting off).

03-06-2023, 06:05 PM	#1
sstephen17 Drives: 2014 Camaro 2LT/RS BRM Join Date: Feb 2014 Location: California Posts: 215	P0420 on replaced catalytic converter Back in 2019, I had the P0420 code with bank 2 efficiency. Since I'm in California, the emissions warranty is good for 8 years (2014 Camaro LT). I took it to the dealer and they said they had to replace the catalytic converter. Mileage was 47,000 at the time. In February of 2023, I got the same error code but this time with bank 1 efficiency. Mileage now is 73,000. I've gotten an oil change, cleaned the TB, MAF, and air filter. Manually cleared the code three times but it always comes back with the same code after about 150 miles. My only mods are a catch can and an Airaid modular intake tube. Took it to a mechanic (non-dealer) and they said I need a new catalytic converter. My question is, does a cat that is replaced by the original warranty get covered or am I out of luck getting it replaced/fixed by the dealerxx?

03-17-2023, 12:48 PM	#7
zmotorsports Hardcore Gearhead Drives: 2013 Camaro SS Join Date: Dec 2022 Location: Northern Utah Posts: 46 View My Garage	Look at your upstream and downstream O2 sensor signals. The upstreams should be switching hi/lo relatively quick and the downstreams should be relatively "lazy", almost non responsive but just floating along and I like to see in the 350mV to around 650mV range. If the downstreams are switching similar to the upstreams then the catalytic converter is not functioning. I also like to shoot the inlet and the outlet with an IR gun. You want to see the outlet approx. 100 degrees Fahrenheit hotter than the inlet side to determine if the catalytic converter is functioning (lighting off). __________________ Mike 2013 2SS/RS

03-06-2023, 07:05 PM	#2
gtstorey Drives: 2010 Camaro SS2,L99, LSA SC Join Date: Aug 2017 Location: Huntsville, AL Posts: 2,155	Does it not have a separate cat for each bank? Sounds like it probably does based upon the bank 1 and bank 2 description.

03-06-2023, 08:53 PM	#4
sstephen17 Drives: 2014 Camaro 2LT/RS BRM Join Date: Feb 2014 Location: California Posts: 215	Thanks for the info. I have to do smog next year (did it in 2021) so I'll have to make a decision on paying for a new cat before then or getting a new car, which my wife and I planned to do sometime in 2024.

03-14-2023, 06:10 PM	#5
TommyTheCat SHKE BKE Drives: 2013 Camaro Join Date: May 2014 Location: SoCal Posts: 3,108	could also be a defective O2 sensor, pretty strange for your cats to have worn out so much on the same bank again. you ever drive the car with the engine light on for rich codes or misfire codes?