Yes, my CEL has returned. I tried a fix that WATRD suggested and it got rid of the problem. I got another CEL this afternoon and instead of P0440, P0441, and P0446 it was just P0446 by itself.
Leads me to believe that Rob's fix did work but maybe I had an underlying problem.

Anyhow, here's the error code:
P0446 Evaporative Emission Control System Vent Control Circuit Malfunction

Does this sound familiar to anyone?

 

what was the original problem?

 

https://www.yotatech.com/forums/show...&highlight=440

 

The PCM monitors that circuit for invalid values by monitoring the ground side of the solenoid circuit for volts or no volts, when properly operating the computer expects to see battery volts when it commands the solenoid off and .5 or less volts when its on, if it does not see the right values then generally within two drive cycles it will turn on the MIL. I would get a wiring diagram of the circuit and start testing it, for example, find one of the wires at the ecu and find the same wire at the solenoid and hook up a ohm meter to one end of the wire at the ecu and the other end at the solenoid it and see if you have continuity, .5 ohms or less is a good reading, and do the same to the other wire, if one is open you will have to find connectors in the truck to start "Halving the circuit" and start isolating it down to a piece if wire or connector, also you will need the ohm spec for the valve itself, to make sure thats not bad. I hope this helps, Joe

 

Oh man... electronics?
Dang, I guess I'll have to learn how to use a voltmeter.

Thanks Joe, I'll look into it.

 

Anyone know where I can find this wiring diagram? This thing is driving me nuts!!!

 

If you know someone at the dealer, they may print you up a copy, or you could see how much toyota wants for their factory service manual , i wouldnt use wiring diagrams out of chilitons or haynes, because they are usally wrong , i have a friend that is still going to UTI, i will talk to him and see if he can get it off All Data for ya What year is your taco?

 

Peter -

I dont get it, shouldn't this be covered under that Evap campaign that Toyota has going right now?

 

Peter, here is what I get for each of the codes:

P0440 - Evap Emission Control System
P0441 - Evap Emission Control System, incorrect purge flow
P0446 - Evap Emission Control System, vent control circuit

I suspect as you did that the first two are from topping off the tank but the last one could be something else. You may also need to get a Factory Service Manual (FSM) to troubleshoot the wiring and to know what signal the ECU should see vs what it does see (ie why it shows the code). Maybe if someone is nice they can scan you the wiring diagram and the section on the evap system and post it.

Edit: seems like your problem has happpened to others:

I went to my appointment at the dealer today and it turns out the problem was along the lines of what MTL suggested. The VSV valve was stuck open. Replacement part $44, labor $150. But what are ya gonna do? I have no idea what a VSV valve is or where it's located so I couldn't very well fix it myself.



Here's the thread:
https://www.yotatech.com/forums/show...ighlight=P0446

That should be your problem right there!

 

I looked for that campaign and haven't found anything on it

 

MTL-
Thanks dude, I'll have to go check it out. Anyone know how you can tell if the part is bad? The valve itself I wouldn't mind replacing BUT my CEL is supposedly pointing out that a circuit is going lame too.

Just an FYI - I've reset this dang thing like 15 times now. I'm averaging 25 - 100 miles per appearance.

 

Oh yeah, I guess I forgot to mention (it would make the above post make more sense)

Since the first post I've gotten a whole series of combinations of codes all revolving around the same 3

440 and 446
440 and 441
just 441
just 446

:pat:

 

It is only like $40-50 so I would just replace it anyway.
If the light goes away then great if not you can check another item off the list.

Found this too on www.yotarepair.com

Check engine light P0441. This code is becoming more common. It seems to be just Camry's and Tacoma's. You may not be able to duplicate this condition but after several tries you will be convinced. My advice is to read the code and replace the canister since the small valve is blocked from whatever is breaking up inside. We are starting to see some failures with new canisters after several months. You may want to check for how the hoses fit the canister, you may find that some don't fit very tight and a clamp is needed. Note: automatic trans. and standard canisters are different.

Check engine light P0440. This code is fairly common and is caused almost always by leaving the gas cap loose or off during refueling if the engine is running. Normally just checking for the cap and talking to the customer will correct the condition. In later models other reasons can cause the same code so if the cap is tight and the customer has been "schooled in gas cap 101" then you may have to look at loose fitting hoses or some other cause.

 

bump... my CEL came on with p0446 and they said it was the 'charcoal sensor'.

whatever, its warrantied.

 

I'm pretty sure it's the VSV valve as Jamie mentioned. I've been busy with other things so I haven't been able to get the replacement part. I'm also thinking I may have caused it with Simple Green that I didn't wash out well enough...

 

well all i know is, its under warranty, so i guess as long as that light aint on, and its running right, i'll let it go.

good luck.

 

What is the VSV valve? Or am I going to have to go to the stealership?

 

Vacuum Switching Valve.....should be about $50 from the stealer.

 

Is this dificult to replace?

 

No, not at all.
Here is a good link for testing and replacement of it:
http://www.4x4wire.com/forums/showfl...ev=#Post539563

Look at the bottom two 5VZ-FE hose routings for info on where it is located:
http://www.autozone.com/servlet/UiBr...3d80161188.jsp

VSV for EVAP is the one you want