catalyst inefficiency codes, 100% stock

[fragment]

Happened three times now. Going in to dealer tomorrow. Will update ...

 

[blkout]

My 2024 CT5 BW recently threw P4020 code, but only after I installed a JLT intake. I reset the code, removed the JLT intake and the code didn't come back. Reinstalled the JLT intake and the code came back again within a few days. Removed the intake again and reset the code and it hasn't come back since. I've even replaced the right rear O2 sensor thinking maybe it had gone bad, but it didn't change anything either.

My car is going to Vengeance Racing on Dec 1 to have a Magnuson 2650, 103mm throttle body and JLT intake reinstalled, ECM tuned so they will tune it so that the code doesn't come back.

I am curious what's causing yours though if your car is stock. I'm wondering if the 02's are set too sensitive since these cars only have two catalytic converters vs four converters on the ZL1. I've never seen this issue on the ZL1 platform.

 

[fragment]

Dealer has ordered both cats and O2 sensors. I asked if the cats tested bad, and the tech looked at me like i had two heads and said "they tested bad when the light came on". So I guess they're just using the parts cannon and the OBDII logic.

Parts will take about 10 days to arrive. I looked at the cat location and it looks like a bitch of a job.

 

[blkout]

Dealer has ordered both cats and O2 sensors. I asked if the cats tested bad, and the tech looked at me like i had two heads and said "they tested bad when the light came on". So I guess they're just using the parts cannon and the OBDII logic.

Parts will take about 10 days to arrive. I looked at the cat location and it looks like a bitch of a job.

How many miles are on the car? It's really hard to imagine the cats are bad. I think the O2s sensors are setup too aggressive and causing them to throw codes when they shouldn't. A brand new set of cats and O2 sensors may solve the issue for a short period of time but I suspect it will come back again. These cats just aren't that fragile. I understand that the tech has no other answers and it doesn't cost him anything to replace all this under warranty so he's just taking the shotgun approach.

 

[fragment]

Just under 50,000 km

 

[blkout]

Just under 50,000 km

More than I expected but honestly, catalytic converters or O2 sensors should not go bad that quickly unless there was a bad run of cats during some point in the years these cars were manufactured.

 

[TERRAVAST4]

Have you checked for any saved codes for misfires? Was it throwing the code random or possibly after spirited driving?

 

[vagabond]

Folks have had catalytic converter issues on the forum. Especially when WOT a lot. I've had mine replaced. Ask them to check your plugs.