Check Engine Light Code P0420

[Fray_s550]

Hello,

I’m seeking help regarding this issue. I installed a new catback exhaust system on my V6 about 3 weeks ago.. everything was going perfectly fine until I got a check engine light 2 days ago. I had it checked and it came with this code P0420. Is this an O2 sensor issue or something else? I feel like the car is behaving differently since the light came on. I can almost say that it feels like misfiring but I’m not too sure. Any help would be appreciated.

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[BlueDevil2016]

Just a place to start in what I found online:
A code P0420 may mean that one or more of the following has happened:

Leaded fuel was used where unleaded was called for (unlikely)
A damaged or failed oxygen / O2 sensor
Downstream oxygen sensor (HO2S) wiring damaged or connected improperly The engine coolant temperature sensor is not working properly
Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe
Failed or underperforming catalytic converter (likely)
Retarded spark timing
The oxygen sensors in front and behind the converter are reporting too similar of readings
Leaking fuel injector or high fuel pressure
Cylinder misfire
Oil contamination

 

[Fray_s550]

Just a place to start in what I found online:
A code P0420 may mean that one or more of the following has happened:

Leaded fuel was used where unleaded was called for (unlikely)
A damaged or failed oxygen / O2 sensor
Downstream oxygen sensor (HO2S) wiring damaged or connected improperly The engine coolant temperature sensor is not working properly
Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe
Failed or underperforming catalytic converter (likely)
Retarded spark timing
The oxygen sensors in front and behind the converter are reporting too similar of readings
Leaking fuel injector or high fuel pressure
Cylinder misfire
Oil contamination

I came across this information too. Too many possibilities but honestly I’m thinking it could be spark plugs cuz they’ve never been replaced and the car has 54k miles. I refuse to believe that the cats failed on a 2015 performance vehicle lol

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