Good ol' P0446

[Elan750]

you guys gotta read this article like 6 times...
Be a Toyota leak detective - Automotive Service Professional

I had a leak and fixed it for $20 bucks.

I wrote down my progress here:

http://www.toyota-4runner.org/4th-gen-t4rs/223147-code-p0456-when-its-not-gas-cap.html


Also the TSB pdf files are helpful to test the cannister/valves with a 9v battery.

 

[AZBub]

An intermittent p0446 is most likely hairline cracks on the vapor can. It is true that even testing the VSV with a 9v can be misleading. Even if it clicks the rubber seal inside could be old and cracked.

The whole emissions system is susceptible to wear. It wouldn't hurt to replace both VSVs and get some new lines, check the can for cracks. If there aren't cracks apply JB weld to the seams anyways. Still way WAY cheaper than getting a new one from Toyota of Doorman.

Our 3gs are 16+ years old now. Looking at sensors, lines, wires and switches is a good idea of preventative maintenance.

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[Ironman707]

An intermittent p0446 is most likely hairline cracks on the vapor can. It is true that even testing the VSV with a 9v can be misleading. Even if it clicks the rubber seal inside could be old and cracked.

The whole emissions system is susceptible to wear. It wouldn't hurt to replace both VSVs and get some new lines, check the can for cracks. If there aren't cracks apply JB weld to the seams anyways. Still way WAY cheaper than getting a new one from Toyota of Doorman.

Our 3gs are 16+ years old now. Looking at sensors, lines, wires and switches is a good idea of preventative maintenance.

Sent from my iPhone using Tapatalk

I was actually thinking of getting some new hoses, now that this happened I'll be motivated to actually do it now

 

[AZBub]

silicone intakes has a kit. you don't need the big one. if you use silicone lines use them for the emissions side only.


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[fourfive]

The FSM has steps to check the VSV using a multimeter and blowing air into it. I did the 9v battery test first since it was quick and easy but also used a multimeter. The FSM also has instructions for testing the charcoal canister.

 

[AnotherCO4Runner]

An intermittent p0446 is most likely hairline cracks on the vapor can. It is true that even testing the VSV with a 9v can be misleading. Even if it clicks the rubber seal inside could be old and cracked.

The whole emissions system is susceptible to wear. It wouldn't hurt to replace both VSVs and get some new lines, check the can for cracks. If there aren't cracks apply JB weld to the seams anyways. Still way WAY cheaper than getting a new one from Toyota of Doorman.

Our 3gs are 16+ years old now. Looking at sensors, lines, wires and switches is a good idea of preventative maintenance.

Sent from my iPhone using Tapatalk

New guy here. I have been resetting the CEL for this error code for about 8 months now. Is there any harm in not addressing the issue? It seems like a lot of chasing down and replacing stuff that probably won't solve the error.

 

[Marine1958]

P0446: Light came on at about 100,000 on my 98 Toyota 4-Runner with code P0446, since I always TOP OFF my gas tank since the auto filler QUITS when I'm 4.5 gallons from full which of course filled up the evap tank! The smog check said it was the gas cap, which I replaced and which kept the code from coming back for about another 20,000 miles....now over 200,000 miles and it comes back on all the time, so I just WIPE it out from time to time with my code reader and since I NOW don't have to pass smog in my state I don't worry about it....still runs great and gets over 21 mpg with good gas! Use Mobil one and change at 8,000 miles, sent in an oil sample to Blackstone who suggested trying changes at 10,000 miles!

 

[Ironman707]

Need advice

Well I got this code and my scanguage gave me the code, I replaced both valves under the hood and got a new canister straight from Toyota and today I got the check engine light on again. And yes gas cap was replaced as well.

Does anyone know what else it could be??

 

[ThrasherSOWT]

New guy here. I have been resetting the CEL for this error code for about 8 months now. Is there any harm in not addressing the issue? It seems like a lot of chasing down and replacing stuff that probably won't solve the error.

HEY! That's why I'm here too.

Mine came on days ago, went to Autozone, got my trusty "P0446" and then did some basic research, realized it wasn't a simple fix, and went to a local shop.
They replaced once hose to my airbox, and it went away...
And then came back this AM.

I'm ok with taking it back, though I can't sink lots of money into this at the moment, but I have a question to all P0446 sufferers;
Does your fuel consumption go to crap when the light comes on, or am I imagining things?

This is my first 4R, I adore it, and I swear I'm sold on these things, but I DID buy this one with 220k on it, so, yeah.

Thanks - T

 

[chottinger]

I solved mine with a gas cap. I didn't clear my CEL for a month or so and when I did I got a code immediately that turned out to be completely unrelated. Overall the gas cap is a $10 attempt so it's worth the try

 

[MKtoad]

I have read a whole bunch of threads on this subject in various places. They all seem to end up with a crack in the canister either under the hood or by the gas tank for the newer models. I would suggest that anyone give it the ol' college try with re-sealing the canister. It is about as low cost of a fix as you can get, and sometimes you can't see cracks to even know they are there. This would always be step one for me anyways...

I just have to give a solid to this forum and maybe help save others time and money like this did for me. I spent a ton of time researching my P0446 code, read this whole thread plus some more. What this man speaks is the truth. I couldn't see the crack just looking, but once i pulled it out, that hairline crack was there. $7 on plastic JB weld, cleared the code, drove around until I hit 400 miles or so, and it passed CA emissions. And... the light still is off! Super easy and saved me a bunch of $. Thanks to you all for your input.

 

[rmartin929]

Easy Way to Test for Hairline Cracks in Canister

Solve your P0446 easily: 1999 Toyota 4cyl 4runner EVAP Canister fix P0446 - YouTube

Had the P0446 for years. I read forums, chased down vacuum leaks, and tested canister valves - I did conclude it was the canister. But, I got into the habit of clearing the OBD and driving just the "right" amount of miles to pass emissions before the check light returned. Today, emissions test due, and I had tracked down a 4runner at a junkyard to go pull/buy the canister. Thought I would review a vid on replacement 1st and came across this as I was getting ready to leave. Did the spray test and bingo! I had leaks on both front corners! I really love fixing stuff vs. trashing it. JB plastic weld, passed emissions, exhaust literally smells better; and I'm confidant this was the cause of P0446 and a great solution.