I’ve got a 2019 F150 3.5 eco-boost with about 200,000 miles. Two times over the last week when I have been driving, the engine starts missing like it had bad gas for about 5 to 10 minutes and then drives perfectly fine again. This happened a few days apart. When I got in the truck yesterday, the check engine light was on and the code was the bank two catalyst below efficiency. I’m trying to figure out what caused the code and I doubt it is anything to do with the actual converter as that would be a more constant problem. Has anyone had similar issues? I was thinking maybe the two rear O2 sensors could be having a fault but I do not think that would cause a misfire since the front ones are the ones that regulate the fuel air mixture.

 

You cannot second guess the system.
The 430 code sets when the rear Ox Sensor detects to much Un cleaned exhaust >> not enough Oxygen.
This causes the rear Sensor to begin to very it's output and foo follow what the front Sensor does.
Therefore the >signal Ratio between them goes down.
When this goes outside limits, the code is set.
.
It could be misfires for too long a time.
Raw fuel combusting in the Cat, overheating the substrate.
Oil contamination.
Broken Cat substrate.
It is foolish trying to second guess the system before repairs but find out if there are other causes before installing a replacement only to have it happen again.
Good luck.