Code: P0446

Code: P0446

I have a 99 corolla and earlier this week my CEL light came on. Using the OBDII scanner tool I got a p0446 code. Evap. What could be the cause of this and what can I do to fix it? Thanks for any help.

ok im gonna tell u how to fix permanently and this does work cause i did do and and the code is gone

ok so the problem is u need to replace the VSV (vaccum switching valve) in the back of the car. NOT the one in the front it will only cost u money to replace and waste of time. This is a special order part and ull have to wait a few days to get it at toyota. Here is the code 90080-91186 just take the number down to a toyota dealer and order the part its like 35 bucks. or u can order the whole canister for like 200+ but that requires u drop the gas tank i think and a lot more work, if u want the code for the whole canister 77740-02102 once u recieve the part now comes the fun part. ull need to jack up the back of the car if ur gonna do it in the driveway. but if u have a lift that will make this ten times easier. now next to the gas tank ull see a black box thats the charcoal canister. attached to that is the valve u need to replace its a major main to get to the valve u pretty much need to undo all the hoses on the canister to get to the one screw holding the thing on. but ull also have to bend the bracket that it sits on becuase ull never get a screw driver in there i had to use a swiss army knife w/screwdriver to get the right angle to unscrew it. once u do that its easy put new one in bend bracket back and ur done go to advanced auto parts and clear code. all in all it will take about hour and half 2 hours if done on driveway

here are some pictures of the valve and canister sorry no pics of under car

Hey thanks for the help!! I'll definitely go get that part ordered and my friend has basically everything but a lift at his house. So it should be somewhat a quick install.

good luck, it sucks you have to do under the car stuff, as apposed to engine bay stuff which is much easier haha, props to you for it looks like a tricky job

My friend and I installed springs and did brakes within about 2hrs tops.

^^^ Let us know if replacing the CCV-VSV valve helps with the P0446 code.

Some common culprits that will set the code are:

As perviously mentioned - the CCV-VSV (Closed Canister Valve - Vacuum Switching Valve) - bad valve will not hold pressure or cycle properly.

A bad tank cutoff valve or sometimes called a fuel tank overfill check valve (sits on top of the gas tank) - is a common problem on Corolla (MR2, Echo are also affected by these). This was the case in my car - you can undo a tank strap enough to drop the tank to get at the valve on the top. If you can pressurize the tank - you can squirt soapy water everywhere and look for bubbles. Bubbles = leak and a potential culprit.

Worst case - you have a damaged vapor canister (little more than a charcoal filter in a box, there are all sorts of diaphams and stuff inside - exterior case could be perfect, but it could be busted on the inside).

well the gas tank one is not as available to salt and sand so most of the time its the vsv. but b4 i replaced mine i noticed when i take the gas cap off there wasnt a pressure like air hissing in like my mothers sienna and i wondered if that was right, and after i put the new vsv in its is def sealing and pressurizing the system likes it supposed to be.

but take his point u shouldn't overfill it a lot some but not crazy it will damage that valve too

I got an evap because I installed a brand new 4-1 racing header, I don't know why I bought that but yeah, and the cel came on for evap, it went off all by itself later on.

Yeah the couple of times i've filled up on gas I've noticed there's no hissing sound when removing the gas cap. Thanks for all the help guys!!

Well the code magically went away yesterday...

haha. I am guessing Corollas do that a lot. They(the Corolla's ECU) should probably wait before showing a Check Engine Light.

mine did that at first i had taking my car into the the body shop and the light came on while i was bringing it over, i got it back 2 days later and it was off. went and check it 0446 code, cleared just to be sure then 2 days later went off again and stayed on this time so. if ur stays off thats good but id say it isnt fixed

Are there any side effects if you don't get this code fixed? or big problems down the road?

well other than the cel being on all the time i dont think so but u will not pass emissions if ur state has them. i really couldnt tell if it messed with mileage cuz my car had other things wrong wit it so

I haven't heard the hissing in mine for a long ass time :-/

Yeah, I have a scangauge though so I can just turn the CEL off whenever and right before an inspection lol.

I have it plugged in all the time, double stickied on top of the steering column.

Still no CEL for the code after 3 weeks... goofy ass corolla.