I just had this issue with my truck that I just got 2 weeks ago...had to go back to the respective dealer 4 times to get it fixed. They originally put a vent valve in it and that didn't fix the CEL. They finally diagnosed it instead of guessing and found that there was no power getting to the fuse box. There was a wire that ended up being disconnected somewhere in the harness. They ended up running a wire from the fuse box to the cannister. I saw a video on YouTube where a guy had the exact problem where he yanked on a harness near the back of the truck and one of the wires was just frayed and came right out. Anyways, it's been 2 days without the CEL so I'm assuming it's finally fixed.

I would check if you have power at your fuse box. If you already did this and stated here in a post, I apologize for not reading all the posts and wasting your time. Hahaha.

 

When It was coming on speratically a while ago I have power to the canister when the CEL was on.


Now that it is on constantly I will check it again to see if that is the cause.


You don't happen to know the fuse do you? I looked up in my manual and the closest I got was possibly fuse 26 but it had a few things on it so not sure if that is the one.


Thanks

 

I don't know off hand but I may be able to check in the morning. I will have to locate my fuse box but that shouldn't be too hard and then I can see where the guy wired it.

 

So here is the latest.


The CEL is coming on cause it is not getting enough voltage to the solenoid.
It should be getting at least 12, but at best only getting 8.5v.
tracing the wiring I am getting 12 v from the battery to the fuse (in the fuse box) I am also getting 12 v from the fuse to a wiring harness connection that is attached to the drivers side wheel well on the engine side. but I can only get 8.5 v from the connection to the solenoid.


So I hardwired the solenoid right to the battery (with an in line 20 A fuse) right to the battery. And the CEL is gone. and has been gone for about a week now. So I will now do a more permanent connection sometime in the next couple weeks.

 

So I got the po446 pulled the power and one side of the hose I got zero suction so that's good pulled it all the way off it seams to open and close fine I get 19 ohms the power is only 10.7 from the connector is that enough to not open the valve all the way and throw a code?

 

My check engine light came on today. Plugged my code reader up and have the same code. Similar to you. It’s muggy and has been raining here all day. I’ll see what tomorrow brings when it’s dry out.

 

Just read out P0446. CEL on my 2018 2.7 first came on as I was pulling out of gas station after filling tank, from about half full. How does that happen if EVAP check is performed between 3/4 and 1/4? It was definitely not on before I refueled.

 

P0446 is an electrical circuit fault related to the canister vent valve and is checked as part of the CCM (Comprehensive Components Monitor), not the evap monitor test.

This DTC has nothing to do with the purge valve or the gas cap or the filler flap or the weather.

 

I wish I had seen that reply before I went to my local Autozone and spent $50 on the solenoid that IT said I needed, because it didn't fix it! I have seen a couple of Youtube videos stating there is a common wire fault underneath the vehicle at the back, I have fished around at the looms there and replaced some of the shielding but I can't find the cables they show in the videos, is it different on the XLT 5.0 with the massive gas tank? I would like to see if the broken wire is the cause but I'm at a loss as to where exactly this actual section of the wiring is. If anyone can advise I'd really appreciate it. Tks.

 

The usually reported location for the wiring issue is within a foot or so of the canister vent valve. Find it and trace the harness back a ways checking it for wire breaks inside the insulation.