I have had EVAP OBDII codes 441 and 446 on and off again since July. I have put a new OEM gas cap, and read on here about not over filling the tank and I have not filled it up in 6 months. I can clear the code and it will pop up every week. I took it to a Toyota specialist and they could not help and said I should take it to the dealer and just start replacing parts. Seems to be a problem on the later 3rd gens because they moved the cannister above the spare tire and lower than the filler neck and it just gets flooded if you top it off. I feel that the reason I have my car is because the previous owner could not fix it either. It popped the week after I bought it. it is past it's 8-year 80,000 mile EPA mandated emission warranty so I am out of luck there. Has anyone had this problem and been successfull at fixing it.

 

throwing parts at it is the lazy mans way of trying to fix something. Doesnt sound like a toyota specialist to me.... Anyways, check all your vac lines going to the canister, make sure your gas cap ratchets down, and if all that is good, i'm willing to bet your evap canister assy is no good. When it starts coming apart inside, little specks of carbon get stuck in the vsv's causing a problem. If you replace the evap canister make sure it comes with all the vsv's. You wont be able to clean out the old ones. I have replaced many canister assy's

 

I tried taking the evap cannister off and I was able to get one line off and I tried to air it out, but I guess if parts get loose than that may be my problem. There are so many lines I just quit. Are there special tools to get some of the lines off, they seem like AC or Fuel lines but much bigger.

 

i dont think you need any special tools for that. The lines should just come off. Yah..you can air out the canister. The carbon breaks up inside and thats what ruins everything

 

X2

I've seen people try and clean out the canister, but all it does is keep the CEL off for a few more weeks. Either get an EVAP assembly from a junkyard (not always guaranteed to be good though) or get a new one from the dealer to fix. Toytech is right, fix it correctly or it will keep coming back to haunt your dash.

Here's right from the FSM:

CIRCUIT DESCRIPTION
The vapor pressure sensor, VSV for EVAP, VSV for canister closed valve (CCV) and VSV for pressure switching valve are used to detect abnormalities in the evaporative emission control system. The ECM decides whether there is an abnormality in the evaporative emission control system based on the
vapor pressure sensor signal.

DTCs P0441 and P0446 are recorded by the ECM when there is a malfunction in either the VSV for EVAP, the VSV for pressure switching valve, or in the vapor pressure sensor itself, or when evaporative emissions leak from the components within the EVAP components.

DTC P0441 Evaporative Emission Control System Incorrect Purge Flow
The ECM closes the CCV and opens the VSV for pressure switching valve causing vacuum to increase in
the entire EVAP system. The ECM continues to operate the VSV for EVAP until the vacuum is increased to a specified point at which time the ECM closes the VSV for EVAP. If the vacuum did not increase, or if the vacuum increased beyond the specified limit, the ECM judges the VSV for EVAP and related components to be faulty.

DTC P0446 Evaporative Emission Control System Vent Control Circuit
When the vapor pressure rises to a specified point, the ECM opens the VSV for CCV. Pressure will increase rapidly because of the air allowed into the system. No increase or an increase below specified rate of pressure increase indicates a restriction on the air inlet side. The ECM closes the VSV for pressure switching valve. This action blocks air entering the fuel tank side of system. The pressure rise on the fuel tank side is no longer as great. If there was no change in pressure, the ECM will conclude the VSV for pressure switching valve did not close.

 

You need a scan tool with active testing to properly test the solenoids. Listen for the click. If you don't hear a click when they're 'applied' by the scan tool, unplug them and plug in a noid light to check for power/ground.

Failed VSV or faulty canister assembly are the usual culprits. Test first because those canisters are hella expensive.

 

well thats true but not always the case. The vsv's can still click but may not be working properly due to carbon inside them.

 

So is the vsv under the hood on the 02 or down by the cannister. I have taken both valves under the hood out and cleaned them and I think I hooked them up to 12volts to hear them click. It has been a while.

 

My EVAP is omitting an odor and I think its time to replace it.I have owned the truck since I purchased it off the lot in 89.So I think its time. It was a California Vehicle. The part is around $250.00 for just the canister.

Ouch.

 

I have a 1997 tacoma and the light just came on. It gave me a code 446. Is this something I need to fix right away? Will it hurt anything if I wait?

Thanks

 

I have a 1997 tacoma and the light just came on. It gave me a code 446. Is this something I need to fix right away? Will it hurt anything if I wait?

Thanks