P0445 and P0449 CEL and TRAC

Can anyone confirm what I already think is the problem? I replaced my gas cap with a locking cap, I only drove it maybe 5 miles. Friday I get in the truck and I have CEL and TRAC warnings.

My assumption is that the locking gas cap caused the VAC to fail test. I reset the lights and drove it around the block and it’s ok so far. Is it possible that I got a vented cap vs non vented or vice versa that caused this?

 

Since it happened after you installed that cap that's likely the issue, locking gas caps are hit or miss with sealing from what I've seen.
Put the stock cap back on and see if the codes stay gone, the EVAP leak test runs aprox 3-5 hrs after the engine is turned off so it may take several days for the codes to reappear after being cleared.

 

I cleared the code and put the stock cap back on and its good to go. So Duralast #5791 from AutoZone doesn't work on my truck. I'm reading that Stant #10504 works but not the knockoff version. I can't seem to find one, people are saying that a square key is a true Stant and a round key is a knock off. I've found several caps with the part #10504 and they all have round keys. I realize that locking the cap risks someone drilling the tank, but I think it will at least keep the amateur thieves at bay.

 

I used an aftermarket locking gas cap for 12 years on my 2010. Stant as I recall. It would throw a P0456 about every 6 months with that cap. Just recently, it also threw a p0455 and a P0441.

After consulting with my mechanic, I went back to the factory gas cap and it has been clean since. Seems to get very slightly better mileage too. Still too early to be sure that the cap solves it all. I'll likely know on Saturday when temps spike again. It has tended to throw these codes on hottest days in this last while.

But yes, I'd say your truck and gas cap combo are not compatible. And in this day, if they can't siphon, they're likely to drill your tank. That's a lot more expensive to fix than to replace a tank of gas, even at current prices.