I had no issues parked outside all winter. Then came last Sunday into Monday an it got ridiculously cold. Drove it at 630 pm last Sunday got home and my wife started it in the morning at 6am and said something was weird. I went and started it at noon and it would barely idle. I could smell fuel. Drained my oil yesterday since it was a balmy 30 degrees and it definitely had fuel in it. New oil and filter then Started it back up and it ran good for two minute and then did the same thing with the above codes. Any ideas? It's an 04 6.0 with 70k miles.

 

30 degrees farenheit?

 

I've never diagnosed issues in that sort of weather before, but I'd be willing to bet that there's water in the fuel and one (or more) of your injectors got frozen open.

 

Ideas on how to diagnose? It was up to 37 and still had issues. We dumped heat in the tank and let it run but no improvement.

 

Based on the codes, it sounds like a leak in the intake tube (post MAF) or in the intake manifold. Most of the time, bad intake gaskets cause P0171 & P0174 codes, so I'm not entirely sure on that diagnosis, but it's a direction to look into.

My truck, unfortunately, spends many hours in cold weather like this (it's 14*F now, but was between -40*F and -60(F for a while around New Years) and I've never had any of these issues with the actual performance of the sensors. I had the aforementioned codes when I bad intake gaskets, but it would only cause a stall on cold start but it would all go away once it warmed up.

 

My truck has just sat since the issue. Now it's 40 still the issue. Runs great for the first minute but then struggles and starts to miss. No cel currently. Can def still smell fuel