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.
