Good ol' P0446

[shahsmerdis]

Does anyone know of a cheap toyota techstream device, are the 30 one's on amazon and ebay worth it?

I want something with bidirectional controls, I as hoping to do a video or write up on Evap codes but i need access to the fuel tank pressure sensor and some sort of bidirectional controls without the 1k+ dealer scan tool.

it should be able to help hunt down a evap codes.

Thanks.

 

[shahsmerdis]

Have this same code for a 2002.
Changed gas cap, code came back.
Replaced canister with good condition (no cracks) one from junk yard and switch next to it.
Code came back 55 miles later.
Does anyone know the part # for the two vacuum switches under the hood? I'm also hearing a noise under the hood.
Thanks.

https://www.amazon.com/Genuine-Toyota-90910-12245-Vacuum-Switch/dp/B00GJJKUWY/

https://www.amazon.com/gp/product/B00KTKF86W/


you may need to double check with your vin if that is the right ones. but i think they are for 02.

 

[shahsmerdis]

Have this same code for a 2002.
Changed gas cap, code came back.
Replaced canister with good condition (no cracks) one from junk yard and switch next to it.
Code came back 55 miles later.
Does anyone know the part # for the two vacuum switches under the hood? I'm also hearing a noise under the hood.
Thanks.

https://www.amazon.com/Genuine-Toyota-90910-12245-Vacuum-Switch/dp/B00GJJKUWY/

https://www.amazon.com/gp/product/B00KTKF86W/


you may need to double check with your vin if that is the right ones. but i think they are for 02.


this is what is annoying about this code, its pretty common, and so many many things can go wrong with it. There is a procedure for finding out what exactly is the issue, and its hard to tell someone to just throw a canister on it. I keep seeing posts but no diagnostically procedures to help attack the problem without proper tools, it really is a crap shoot.

 

[Thrashpipe]

02 4runner sr5 4wd

Hey guys my turn.
I'm new here and brand new to toyota, i LOVE my 4runner but I have the dreaded vsv code. Now with the knowledge from "Rockslide" and some testing I have found my rear valve does not respond to voltage at all. So that one is obviously bad. However, I have a strange and probably stupid question about my 4wd. I suffer from a problem with my 4wd engauging and disengaugeing. Now, knowing that they are assisted by a vaccum line, are they in anyway linked?
(a side note to include is my front dif's vacuum line goes to a factory plug stop, but the transfer case actuator actually goes into something up top of the t case I can't see, only feel)

now, I ask this question because more than once now I have had the CEL come on when I attempt to engage my 4wd. Is this in any way related or just mear fluke?
Thanks in advance guys! Love it here!

 

[ElBrio]

https://www.amazon.com/Genuine-Toyota-90910-12245-Vacuum-Switch/dp/B00GJJKUWY/

https://www.amazon.com/gp/product/B00KTKF86W/


you may need to double check with your vin if that is the right ones. but i think they are for 02.


this is what is annoying about this code, its pretty common, and so many many things can go wrong with it. There is a procedure for finding out what exactly is the issue, and its hard to tell someone to just throw a canister on it. I keep seeing posts but no diagnostically procedures to help attack the problem without proper tools, it really is a crap shoot.

Thanks. I actually found these and ordered from amazon, should be here Saturday. What a crap shoot this is. I have already replaced the canister with a new to me one, vacuum switch next to it, and gas cap. I've also check all lines with no rips or anything.

 

[Merninater]

Smoke Test First

My experience with this code,

I had this code plus the other two emissions codes for a while now. Had the smoke test done after failing to clear the code by replacing the EVAP unit and then the filler neck. Smoke test revealed massive holes (like 2 inches long) in the plastic ribbed hose that goes from the top of the gas tank back to the evap unit. Replaced this hose a few days ago and i am praying that is the end of this issue.

My advice with this problem is to immediately take your car to toyota and have the smoke test done. Then fix the problem yourself. I should have done this from the get go and I may have saved hundreds of dollars.

 

[shahsmerdis]

My experience with this code,

I had this code plus the other two emissions codes for a while now. Had the smoke test done after failing to clear the code by replacing the EVAP unit and then the filler neck. Smoke test revealed massive holes (like 2 inches long) in the plastic ribbed hose that goes from the top of the gas tank back to the evap unit. Replaced this hose a few days ago and i am praying that is the end of this issue.

My advice with this problem is to immediately take your car to toyota and have the smoke test done. Then fix the problem yourself. I should have done this from the get go and I may have saved hundreds of dollars.

you probably had a code for leak in addition to the p0446. forgot the code number but the one for large leak. But! if you had bad canister as well, the computer might not have been able to seal your gas tank to determine that. its hard to say.


I just replaced my rear vent valve. it didn't click or whatever. Hopefully that is the last of it fingers crossed!

 

[Merninater]

you probably had a code for leak in addition to the p0446. forgot the code number but the one for large leak. But! if you had bad canister as well, the computer might not have been able to seal your gas tank to determine that. its hard to say.


I just replaced my rear vent valve. it didn't click or whatever. Hopefully that is the last of it fingers crossed!

I hope this works for you. I am at 7 days since I replaced the hose with the holes in it and I am praying to all of the gods that it will not pop back up in these next few days as my emissions are due in December.

If this doesn't work for you I strongly recommend take it to any shop you trust that can do a smoke/smog test where they pump smoke into your tank and see what the outcome is. It really may have saved me from buying a lot of parts that may not have been needed.

 

[ElBrio]

Just replaced one of the two vacuum switches from under the hood on my '02. The other has a screw holding the mount that doesn't want to move. I'll pb blast that and wait.
Here's to hoping this is it.


Sent from my iPhone using Tapatalk

 

[shahsmerdis]

I hope this works for you. I am at 7 days since I replaced the hose with the holes in it and I am praying to all of the gods that it will not pop back up in these next few days as my emissions are due in December.

If this doesn't work for you I strongly recommend take it to any shop you trust that can do a smoke/smog test where they pump smoke into your tank and see what the outcome is. It really may have saved me from buying a lot of parts that may not have been needed.

thanks man! I hope yours works out for you too. It was probably that hole. You can get an obdII scanner, download torque pro, and there will be a status that readys when your evap system is completed its test prior to bringing it into the an inspection.

When I took the gas cap off, I heard a large vacuum, so I don't think I have a leak. When the rear vent closes, the computer looks if the there is not enough vacuum or too much vacuum to throw a P0441. In my gas I guess it was too much vacuum. I really wish I had the scan tool to do this correctly. but I guess the old fashion battery test worked in this case.

Just replaced one of the two vacuum switches from under the hood on my '02. The other has a screw holding the mount that doesn't want to move. I'll pb blast that and wait.
Here's to hoping this is it.




Sent from my iPhone using Tapatalk

Why are you replacing the valve? those in front generally don't go bad since they are away from gas (in the case of over filling) and salt . Please don't blindly replace things, its very expensive. Pleanty of good material, us the forums, and logic to sort out what the weakest link is.

 

[fourfive]

Gathering parts for a homemade smoke machine to look for a leak this weekend. Hope this thing works the way I have it pictured in my head.

Ordered this service port adapter to check vacuum & run the smoke machine.

 

[shahsmerdis]

Which code did you get?

 

[fourfive]

Which code did you get?

I started out with P0440 back in May 2016, changed the gas cap just for kicks and was code free for about a month. Cel came back as P0446 around July. Cleared it manually then came back as P0440 which I currently have.

 

[Merninater]

My 3 EVAP codes are finally gone and I passed emissions testing today. I still firmly believe if you do not have the fancy code readers that getting the smoke pumped into the system at a shop you trust for their diagnosis is the best first step with any of the 3 EVAP codes.

EDIT: Of course after trying the gas cap.

 

[shahsmerdis]

My 3 EVAP codes are finally gone and I passed emissions testing today. I still firmly believe if you do not have the fancy code readers that getting the smoke pumped into the system at a shop you trust for their diagnosis is the best first step with any of the 3 EVAP codes.

EDIT: Of course after trying the gas cap.

Those fancy code readers are useless without the understanding of the system. I Can tell you based off what I read about this evap code.most people don't actually understands the system. It actually seems the verus does have the option to force a test on our systems, but I don't have one to confirm.

For example, I knew I didn't have a leak because I heard a vacuum every time I took the gas cap off. meaning it wasn't sealing gas tank at the canister. Indicating that was the likely culprit . But without one of those fancy scan tools I wasn't sure.

Now if the code comes back. There probably a most costly repair, and I'll need a scan tool to test it.

 

[Ironman707]

So this code just popped up on me... would anyone happen to know any of the part number for the 3 switches.

Also if it's the canister, would there be a smell of any kind?? I had my windows down the other day when I turned it on to warm up and I smelled a chemical odor, I didn't think too much of it because it was somewhat windy and my windows were down but then this happened today.

When I parked the truck today I got under it right away and checked if I could smell anything under the charcoal canister, I also checked all the wiring and everything seemed fine. My vacuum hoses are good too, no cracks or anything.

Can anyone help me out?? I don't want to buy 3 switches and then end up having to buy a canister at the end of all this

 

[WallyWest]

I've had this code for a while, and have learned a lot about the system. I have also passed several emissions tests. If your code is somewhat random, like mine, just reset and drive about 100 miles. Ideally over several days, several cold starts, a few drives cruising above 50mph. If it doesn't throw the code, PARK IT. Schedule the inspection, hopefully nearby hehe, and have it done. Worked for me and the rest of the year the light stays on.

I'm going to tackle it once the weather warms up. The two most likely culprits are a small crack in the canister, or a VSV. Pull the canister, apply some epoxy or whatever to the seam, hope that fixes it. Check the VSV while it's out with a 9v battery. If it clicks, it's good. If not, replace. Various videos on Youtube on testing the canister while it's out.

New gas cap, might as well. Probably won't fix it.

Then check VSV's under the hood, less likely for them to fail but possible.

If all that checks out and you still are throwing codes, probably need a smoke test. You can DIY that if you want, or pay a shop to do it. If you identify a leak, replace whatever is leaking. I would probably replace the hoses near the canister that are easy to swap out when you pull that anyway, just on general principles.

Bottom line, diagnose, then fix. Don't just throw parts at it. The entire system is rather expensive.

 

[shahsmerdis]

So this code just popped up on me... would anyone happen to know any of the part number for the 3 switches.

Also if it's the canister, would there be a smell of any kind?? I had my windows down the other day when I turned it on to warm up and I smelled a chemical odor, I didn't think too much of it because it was somewhat windy and my windows were down but then this happened today.

When I parked the truck today I got under it right away and checked if I could smell anything under the charcoal canister, I also checked all the wiring and everything seemed fine. My vacuum hoses are good too, no cracks or anything.

Can anyone help me out?? I don't want to buy 3 switches and then end up having to buy a canister at the end of all this

which codes do you have? if you have a smell and you have a code for a leak, then you probably have a leak.

Do not throw parts at this thing yet. Test all 3 valves. start with the one in the rear.

Check the VSV while it's out with a 9v battery. If it clicks, it's good. If not, replace. Various videos on Youtube on testing the canister while it's out.


Then check VSV's under the hood, less likely for them to fail but possible.


Bottom line, diagnose, then fix. Don't just throw parts at it. The entire system is rather expensive.

[MENTION=120497]WallyWest[/MENTION], Sorry if the valve clicks doesn't mean its still good. It can still be partially actuated. still gotta do a vacuum test. but if it doesn't click like mine then it is dead. you do also want to test all the signals to the ECU ensure there is power ground with a scope on a rope.

You are 100% right do not throw parts on this. It is process of elimination using your knowledge of the system.

I'm going to try and see if I can pull up a the fuel pressure sensor live data with the cheap knock of toyota scan tools. If you can then you can see if the gas tank is sealing, and there would be no need for a gas cap. Also this can help people find out if they have a leak without a smoke machine. (You would probably need a smoke machine to find the leak to know what to replace.

 

[Ironman707]

which codes do you have? if you have a smell and you have a code for a leak, then you probably have a leak.

Do not throw parts at this thing yet. Test all 3 valves. start with the one in the rear.




[MENTION=120497]WallyWest[/MENTION], Sorry if the valve clicks doesn't mean its still good. It can still be partially actuated. still gotta do a vacuum test. but if it doesn't click like mine then it is dead. you do also want to test all the signals to the ECU ensure there is power ground with a scope on a rope.

You are 100% right do not throw parts on this. It is process of elimination using your knowledge of the system.

I'm going to try and see if I can pull up a the fuel pressure sensor live data with the cheap knock of toyota scan tools. If you can then you can see if the gas tank is sealing, and there would be no need for a gas cap. Also this can help people find out if they have a leak without a smoke machine. (You would probably need a smoke machine to find the leak to know what to replace.

I ended up with code p0446, my guess is that the canister is leaking

 

[shahsmerdis]

I ended up with code p0446, my guess is that the canister is leaking

Take the spare tire off, and use a battery to check the vent solenoid in the back. It should take about 30 min

if you had a leak, chances are you would also get a p0442 or another code that indicates a leak.