So I have this stupid code and I'm ready to scrap this piece of crap (2018 f150 platinum 3.5eb). Here's a timeline:

Got codes P0451 and P1450: replaced charcoal canister and vent valve.
Got code p0442: replaced purge valve.
Got P0442 again: trusted shop replaced ftp sensor and smoked the "entire system".
Got P0442 again and P0C29: I believe c29 was a fluke and I had no heat or performance indicators of any trouble with thr trans. Cleared them.
Got P0442 alone again: found vacuum line going from purge valve to intake tube was missing it's clip at the intake side. Replaced it and cleared code. (idk how that didn't smoke...)
Got P0442 again and I'm running out of things to check or replace. Any thoughts? Any other ways I can test without smoke myself?

It's worth noting that at no time have I had any performance or fuel economy issues, no significant fuel smells anywhere. I checked the fuel filler door which looked clean and I can feel/hear that it seals when I push it open but I did Ford's "cleaning" procedure anyway. Im over it and have wasted like $700 on parts from cheapest to most expensive going down the list of likely culprits to no avail.

I know there's plenty of threads on this but they all swear the fix is something I've already done.

 

Did you replace the leaking gas cap, or if you have the capless fulling port they can clog up with debris or just start leaking.

Something like this that fits your filler neck diameter would be a cheap way to verify the problem without a complete teardown and replacement of the capless system.

 

Here again, the code description has not been looked at for the fault being detected.
Most short descriptions do not give these details.
.
The EVAP system is checked for low leak values. System Pressure Sensor is used for this test.
This code indicates a .040 size leak in the system.
It can be anywhere between the Capless fill, tank , Sensor leakage, vent valve, hoses on top of the tank, or purge valve and hardware.
A smoke test would not be seen in the tank.
It is an Emissions thing to keep vapors inside the tank, charcoal filter and/or burned off in the engine by PCM Purge Valve control, at the correct time.
This leak test is even monitored while the engine is off in sleep mode by a separate section in Pcm that never goes to sleep.
It detects Tank pressure reductions and increases due to any temperature changes to be sure there is no leak of Vapors while vehicle is not being used.
Its a hassle to find such a small leak but has to be done.
Good luck.

 

I do have the capless system and I have cleaned it and it sounds/feels like it's sealed but I can try something like this. I considered this but wasn't sure if such a thing existed but I guess it does. Thanks

 

"Here again, the code description has not been looked at for the fault being detected."? Tell me how my replacing every part you've mentioned here could be leaking, except the tank, indicates I didn't look at the fault description? You think I'm guessing? Nonetheless, yes I'm aware it's a hassle and has to be done but if a smoke test won't show a leak in the tank, how can I check it because while I was willing to replace all the valves, sensors, and a couple hoses without evidence, I'm sure as hell not replacing the whole *** tank on a whim.

 

The cap referenced in the Amazon link does not appear to me to provide a seal, to the level which is required by emissions testing. It looks more like a dust cap. And, by the lines, it looks like 3D printing. I don't say anything rubber in it. I don't think this product will help you.

 

That's what I was afraid of considering the locking gas cap adapter from Ford is that it just looks like hard plastic with no rubber or gasket material

 

When these left out changes are made, it any ones guess.
I described the operation based on a stock system.
Don't ask how come this or that, I can't answer such replies, for your issue.
Good luck.

 

Seems like a balloon or cling wrap or any plastic baggie plus a rubber band would be enough on the gas filler, just to test it out.

I didn't know about the water remover/vapor catcher/whatever it's called (it's called many different things...but the rectangular thing about 2 feet in front of the gas tank, under the truck). The plug on mine was loose, and I was trying to figure out what it was, in the user manual and then the service manual. Anyways, I'm sure you checked this already, since you've probably traced up the fuel line, but if not take a look at it.

 

You probably could have spent that Same $700 And had a reputable service facility repair it correctly in the first place. Not a wise idea to throw parts at these vehicles.