Code P0446 EVAP System Check Engine Light

[jhowell9618]

My check engine light came on yesterday. I read the code and it was P0446. Has anyone had this happen to their trucks before?

It deals with the evap system for the fuel tank. From what I read online, it’s fine to drive with it, which I guess I’ll have to because the dealer can’t see it until March 9th. This system seems to be emissions/environmental related and not really life threatening for my truck.

The truck has 9100 miles. It drives just like normal. I haven’t tried to fill it with gas, so I’m not sure if this issue will affect that. I just wanted to see if anyone else had this issue.

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[halligan1201]

Others have reported issues with a vent tube being kinked or bent. I don't know if it was the same code or not. You could also check to make sure fuel door is sealing against the fill tube correctly.

 

[Big Blue]

Did you have your truck undercoated with spray liquid? Some people have had issues with the vent getting plugged with the fluid. Don't remember the code, but just a thought.

 

[jhowell9618]

Did you have your truck undercoated with spray liquid? Some people have had issues with the vent getting plugged with the fluid. Don't remember the code, but just a thought.

Thank you for the idea. I haven’t done any undercoating or anything. I did drive in snow/salt this winter, but that’s been about a month ago and just once or twice.
I haven’t been able to look much at the truck since the code showed up yesterday, but tonight I’ll crawl under it and see if I see anything amiss or if there’s anything wrong with the fuel door.

I suppose I could just park it for 2 weeks and drive my Focus, but she’s getting a little rough around the edges, especially in cold weather and the Ranger is a more refined driving experience.

 

[Jason B]

In years past, the number one cause of EVAP system faults was a loose or faulty gas cap. New cars don't have caps, but I suppose it could be something with the filler not seating well. Did you recently fill up?

 

[jhowell9618]

In years past, the number one cause of EVAP system faults was a loose or faulty gas cap. New cars don't have caps, but I suppose it could be something with the filler not seating well. Did you recently fill up?

Last Saturday (Feb 13) was when I filled it up last. It just sorta came out of the blue. I drove about 6 miles to the grocery store and when I came out and started it, there was a check engine light.

Incidentally, are CELs supposed to show up in the FordPass app? Because mine doesn’t show any problems.

 

[harringtondav]

I have the same P0466 code. Seems two possible failures: Canister vent or purge function.
I took it to the dealer and they replaced KB3Z9D289B. Ford pass points paid for my ESP deductible.
I got half way home and noticed the MIL lamp on. ....I figured/hoped the tech forgot to erase the fault.
A week later I was home and checked and erased the same code. It returned shortly.
Back to the dealer. I told them I wasn't interested in paying for an incorrect part. ...we'll see.

 

[RangerBill]

I have the same P0466 code. Seems two possible failures: Canister vent or purge function.
I took it to the dealer and they replaced KB3Z9D289B. Ford pass points paid for my ESP deductible.
I got half way home and noticed the MIL lamp on. ....I figured/hoped the tech forgot to erase the fault.
A week later I was home and checked and erased the same code. It returned shortly.
Back to the dealer. I told them I wasn't interested in paying for an incorrect part. ...we'll see.

That part is the vapor hose assembly. Perhaps the EVAP Canister valve itself is bad or wiring is bad to the valve. From the shop manual:

Second valve in the diagram below:

Connectors C450, C408, and C410 below:

 

[RangerBill]

Someone else was off-roading and damaged the C408 connector (Pin pulled loose from the connector shell) and had a DTC for the first valve in the diagram. You should look carefully at connectors C408 and C410 for damage to wires or pins partially pulled out of the connector shell.

 

[harringtondav]

That part is the vapor hose assembly. Perhaps the EVAP Canister valve itself is bad or wiring is bad to the valve. From the shop manual:

Second valve in the diagram below:

Connectors C450, C408, and C410 below:

Thanks. I also have the CD shop manual and zeroed in on the hose/tube assy and the vent valve at the rear of the canister. ..I was looking for mice wire chewing damage since it caused a similar fault previously.
The canister wire/cable looked good. I didn't have the time or energy to dig out the vapor hose assy. I gave it to the shop in hopes that an EPA warranty or my ESP/Ford pass points would save me the trouble and cost. No cost, but no problem resolution yet.
I got into auto DIY over 50 yrs ago to avoid the shop drama. ...Glad I haven't hung up my tools. ....may need them when the ESP expires in a couple years.

 

[RangerBill]

Thanks. I also have the CD shop manual and zeroed in on the hose/tube assy and the vent valve at the rear of the canister. ..I was looking for mice wire chewing damage since it caused a similar fault previously.
The canister wire/cable looked good. I didn't have the time or energy to dig out the vapor hose assy. I gave it to the shop in hopes that an EPA warranty or my ESP/Ford pass points would save me the trouble and cost. No cost, but no problem resolution yet.
I got into auto DIY over 50 yrs ago to avoid the shop drama. ...Glad I haven't hung up my tools. ....may need them when the ESP expires in a couple years.

Did you check the connectors C408 and C410 and their wiring?

 

[airline tech]

That is code specific -Its either wiring or this valve, most likely the valve itself

Quick Test - (Ohm the valve) itself 40-70 Ohms Specs, and possibly do wiring checks, but my bet is the valve itself.

 

[harringtondav]

Did you check the connectors C408 and C410 and their wiring?

No. Just a visual check for mouse chewing. I'm eight months out of a major spinal fusion procedure. All is good and getting better, but I'm not ready to do much deep digging, but I will be in a few more months. Then I'll be able to check connectors and swap parts until the MIL goes out. ....apparently just like the dealer does.

 

[harringtondav]

Problem solved yesterday after a second trip to the dealer. I told the service manager I don't like paying twice for a repair. Later he informed me they need to replace the fuel filler tube assembly. (???). I asked him if the got the P0456 small evap system leak code. I hadn't seen this, just P0466.
He gave some blah-blah about their pinpoint diagnostics. After several days waiting for the part I went in to pick up my pickup.
No charge for the repair. Tech's notes: "Looked up code and it took me to ppt. HX. Went through ppt. HX and got to HX25 and found dark green wire going to evap vent connector broken".
I was happy about the no charge, and told the SM my only complaint is he poured cold water on the protest speech I'd prepared. He admitted this was likely the problem all along, when they replaced the purge valve assy.
Attachment is ref. for the HX diagnostic flow chart.

 

[airline tech]

Problem solved yesterday after a second trip to the dealer. I told the service manager I don't like paying twice for a repair. Later he informed me they need to replace the fuel filler tube assembly. (???). I asked him if the got the P0456 small evap system leak code. I hadn't seen this, just P0466.
He gave some blah-blah about their pinpoint diagnostics. After several days waiting for the part I went in to pick up my pickup.
No charge for the repair. Tech's notes: "Looked up code and it took me to ppt. HX. Went through ppt. HX and got to HX25 and found dark green wire going to evap vent connector broken".
I was happy about the no charge, and told the SM my only complaint is he poured cold water on the protest speech I'd prepared. He admitted this was likely the problem all along, when they replaced the purge valve assy.
Attachment is ref. for the HX diagnostic flow chart.

Sounds like a good find - the Green wire is the VREF - Signal Return circuit.

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