EVAP codes help

I have a 2003 Toyota Tacoma 4wd with a 4cyl 2.7 liter engine. I have been throwing the following codes for awhile.
P0446 (Evaporative Emission System Vent Control Circuit)
P0441 (Evaporative Emission System Incorrect Purge Flow)
P0442 (Evaporative Emission System Leak Detected)
the P0446 is then repeated a second time

I understand something is wrong with my EVAP system meaning the gasoline vapors are not being fed back into my system because of a leak or a bad purge/shut valve, etc. I have replaced the gas cap and inspected the lines visually for leaks.

I am hoping that with the specific codes, and the information that I only throw the codes when the temperature is above 50 degrees, that someone can point me towards the most likely problem or tell me how I can test the valves without paying for a smoke test. I read something about using a multimeter to trip the valves open and closed, how can I see if they are fully open or closed?
Thank you for any information!

 

anybody have any ideas?

 

look closely at all lines for dry cracked lines at their connection points, I would start there and once that is corrected move on to other codes. these pic are not toyota just examples:

 

I have the exact same issue you are having even the codes only coming up in warm weather and tried all the simple fixes even ordered a 20 dollar electric solenoid that is on the evap canister and tried that with no luck. I broke down and bought a new evap canister off a toyota parts supplier on ebay and just got it today. gonna throw it on tomorrow night and every toyota tech i've talked to said that will solve my problem. here is the link to the one i bought. best price i could find. http://www.ebay.com/itm/TOYOTA-CHAR...Parts_Accessories&hash=item35d482a0c3&vxp=mtr

 

I have visually inspected the lines, but thank you for the detailed information and the time you put into the reply SDsam! Polack, I will be very interested to see if that fixes the problem. Do you think you will have to drop the tank to install? I've heard that it could be overfilling the gas tank which ruptures a diaphragm in the canister, I live in NJ and occasionally a gas station attendant does this. Good luck, can't wait to hear how it goes. Thank you for the link!

 

10 year old vacuum lines? Replace them and the plastic t's. Cheaper than replacing expensive solenoids, only to find that it changes nothing.
You can also test them by plugging one end, and using a hand vac pump to check for leaks.
A visual check will only reveal very obvious cracks. It only takes a small pinhole to ruin your day.

 

i planned on doing my charcoal canister swap today but it's fucking snowing again. Gonna have to wait a couple of days as my garage is filled with other items and i can't get in there. I'll let you know how it goes.\

 

Changed my canister today. Didn't have to remove bed and it only took an hour and a half. after i was done i cleared my codes and took it for a run up the highway. No check engine light. My problem looks to have been cured by the thing everyone says the problem is. The charcoal canister.

 

polack, awesome man. Glad you didn't have to remove the bed. I usually don't get the code until the engine cycles twice. Still not have a code? If not, I might consider dropping the money to get a new canister. I have a code reader, so I clear the code whenever it pops up because I can't stand the light haha, but it would be worth it to be rid of the codes.
I was thinking the other day that I used to also get a suction sound whenever I removed the gas cap. I haven't heard this in awhile. Have you experienced this as well? I hope you continue to be code free. Thanks for the update man.

 

I'm code free. I was like you. I cleared my codes every time that light came on. hated it. I wanted to keep trying everything else to save me the money. In the end i'm glad i got the new canister. I don't smell the gas fumes either. Mine was identical to yours. it would take a few cycles of the engine running to pop the code. sometimes i would get the suction and sometimes not.

 

I've got the same truck only an '02 it's been throwing a P0446 for a while. It first appeared at the end of the summer and I just cleared it every week when it popped up. Come winter (NY) it stayed off for a few months then sure enough first day over 50deg it came back on.

I replaced the gas-cap with an OEM but once it gets under half a tank P0446 comes back. A lot of people have had luck with just replacing the VSV on the canister. An aftermarket Dorman VSV can be had for $25 so it's worth a shot; OEM (Denso) is around $60-$70.

 

mine is an 02 also. i listened to the other guys and bought just that vsv and replaced it. didn't help. Canister solved my issues. gonna guess it's one of the diaphragms.

 

2011 tacoma, small evap leak, Engine and Traction lights on. I replaced gas cap, replaced canister on the gas tank and replace gas filler neck. Still Engine and Traction lights on. Anyone one with suggestions. Also can anyone tell how can I follow the Evap lines to check. Thanks and God Bless