i have a 2014 FX4 super crew 5.0L with 44,000 miles.

at about 33000 miles check engine light comes. by time i took it to dealership light was flashing and p/u was running terribly. tech's look at it and say cat is fried and they put new one on. roughly 4k miles later CEL comes back on. i check it with a cheapie code reader and it shows P0430 again. take it back to dealer and they check it and they say it says overspeed detected and tell me to quit "hot rodding" it. this past friday engine starts missing again and code reader shows P0430, P0300, P0308. CEL flashes when accelerating hard. Take it to dealer today and they say cat is melted and will have to replace again.

Not sure where to go from here, but it seems like they are not getting the right problem fixed. any thoughts or ideas on what i should do to proceeed?

Thanks

 

I can't answer, but are you running it hard ? Sounds like too much fuel to me, but they should be able to detect that.

 

To me it seems like there is another issue not being noticed. It shouldn't be getting that hot. Even running it hard it shouldn't melt in 10k ish miles.

 

misfire is being detected ... a flashing CEL under acceleration...dumping raw fuel into the cat and melting it...

 

That'd be my amateur suspicion - tech has a bit more experience (lol!)

Running rich can clog a cat, but it sounds like you're definitely cooking it.