Trying to fix P0446

[ryhi]

Yes, there is only one valve at the canister. This guys single post explained how to do it and was fortunately the fix for my p0446. I'm glad he posted it because I was about to shell out the $400 for a new canister but instead I only had to replace the valve for $25.

Hello All,

Long time lurker, first time poster.

I had the P0446 code pop up on my 2001 4 Runner Sr5 4X4 and came here to read up on the cause/fix action. I reset the code twice and had it re-appear in a short amount of time (less than 50 miles of driving), so I knew I had a problem, not a fluke. Not being one to change parts for the sake of changing, I did more research as there was no one simple cause.

I found this video - YouTube Toyota P0446 Video - that centers around the same problem, only on a Camry. The basic principle is the same, so I used this as a basis for my troubleshooting.

I removed the canister, which is a bit of a pain, at least on my 4Runner. Spare tire, 4 bolts, one electrical connector, and 6 hoses, if I remember correctly, had to be removed, and some of the connections are in really tight spaces. Still, its not difficult, just harder than it should be.

With the canister out, I performed the vacuum test specified in the video (linked above). Mine would not hold vacuum, hinting that the VCV was stuck in the open position. According to the video I needed to replace the entire canister, but being that I'm not one to top off my tank, I didn't see how the canister was bad, but I knew the valve was. Versus ordering a new canister online for $370, I opted to look for just the replacement valve, and lucky I found that it is available separately, just not from Toyota.

My local Autozone showed one for $42 and could get it within 3 hours (would be delivered from a nearby store). My dad and I ran up and looked at a print out of the piece just to be sure given that Autozone was only about two miles from my Dad's house. Yep, same part, so I ordered it. (Inserted a picture of the part below).

Three hours later the delivery truck arrived, as promised, and I was home installing the piece a few minutes later. Once again I performed the test, and it all checked out as it should - vacuum when closed; apply voltage and vacuum purges, so I (with the help of my Dad) re-installed the canister.

I reset the code and since then have put nearly 1,000 miles on the 4Runner without having the code re-appear. I even plugged in my scanner just to be sure. Yep, still no code(s), so I consider this problem fixed.

I hope this information helps someone else on this forum should they get this code on their 4 Runner.

Cheers!
Merle

 

[Bigmd]

Thanks I've already had the canister in and out so I know what to expect maybe I'll jus order the valve since it's cheap .

 

[ryhi]

I used the same exact part he posted on my 2002 (Dorman 911-601) and replaced the original Toyota/Denso one without issues.

 

[Bigmd]

Quick question and it may be a stupid one. When I put new canister in I wasn't able to mount it to bracket because I didn't have screws from my old one. It's not possible to leak through where the screws are supposed to thread into right

 

[chimpy]

Well, if it makes you feel any better, I replaced the valve at the canister and have now gone from a P0446 to a P0440. I am going to look at the filler neck and see if there is anything going on there. I may have to go to a shop where they have a smoke machine. I don't know where to go with this next.

 

[Bigmd]

Yeah me either . Very frustrating . I was very happy with the truck when I first got it. This however makes me unhappy.

 

[Bigmd]

Ok scanned today and confirmed same p0446. Got truck home and found pcv valve grommet torn. This is 3rd time. Not sure how to prevent since the hole has edge. I'm thinking this ma be prob

 

[Bigmd]

Anyone have a solution to putting pcv in without breaking the grommet? I bought two new grommets and one broke on install. This is 3rd time . Put new o e in and I think it's ok. I put some rtv around it just in case.

 

[AZBub]

Anyone have a solution to putting pcv in without breaking the grommet? I bought two new grommets and one broke on install. This is 3rd time . Put new o e in and I think it's ok. I put some rtv around it just in case.

From what I have read it's easier with the valve cover off, sounds like a PITA. I wouldn't think that that would throw a p0446 but emissions equipment runs on quantum physics so you never really know.

If that doesn't fix your issue I would recommend getting it smoked at a shop ....unless you like cigars and have lots of time.

 

[Bigmd]

Well not surprisingly light on again. Only thing left to do is replace switch at canister ,which I just ordered. And replace vacuum hoses at canister with silicones hoses left over from my kit.

 

[chimpy]

There are 4 bolts holding the canister in place. I was able to hit all but one with some liquid wrench before loosening them. If you see any rust in the area of the canister, definitely use some type of penetrant on them first. There is a small, very small phillips head screw that holds the valve in place. Hit that with some PBB or liquid wrench after getting the canister off of the 4runner. It is so small that the head will strip before the screw will turn. Ask me how I know this. I ended up using vise grips to remove this and used a different screw when I put it all back together.

 

[4Reak Show]

Ok thanks. Read a through those. Ordered the hose kit and new purge valve under hood. Does anyone know the name of second valve under hood? Rock auto has 3 listed 2 of which are at canister. Im pretty sure that's wrong.

Their are 3 total valves/solenoids a for that particular EVAP system: the EVAP VSV (also called purge), the Canister Closed VSV (CCV VSV), and Pressure Switching Valve VSV (VP VSV). If I were you, I would replace the 2 smaller ones you're after. More likely the VP VSV. Its located "under left rear of vehicle" likely near the fuel tank. The purge isn't the issue. That would set a different code. Also, chasing the PCV problem is a good idea overall, but not related to your issue whatsoever. As for how to install the grommet, try Vaseline. I use it almost every day on the cars in my shop on any seal that is used on PETROLEUM fluids (gas, engine oil, power steering, ATF). NEVER use Vaseline on a coolant O-Ring. It WILL destroy them.
Anyway, according to what I'm looking at in my volumes of literature the 2 solenoids switch on/off at the same time in the EVAP testing process so either one could potentially be the culprit.
Also, the EVAP test normally requires an overnight "cold soak" so you will likely not see a repeat light for up to 2 days after clearing the code IF those solenoids don't fix it.
Of course I'm assuming you've double checked all your hose connections yada yada.
Good luck and let us know what you find.

 

[Bigmd]

4reak thanks. I've replaced the 2 valves in engine bay. Have the canister valve on its way in mail. Into under car today and checked hoses, which were checked when I reinstalled with hose clamps where necessary. Any way the plastic corrugated hose that connects to canister was way loose. Almost like it needs to click into place. Came off very easy, not sure if this is causing it.

 

[Bigmd]

Ok was wrenching over here in NJ before 7am haha. Got the new switch from rock auto yesterday. I took the whole canister to my workbench and gave it a good look. Everything checked ok, no cracks and the hoses on the canister looked great. This is definitely a low mileage unit. The only thing I replaced beside the new switch was a small vacuum hose on the T-fitting that goes to the bigger hose on truck. It seemed very loose. If this doesn't fix then I'm at a loss, will probably just cover those lights on dash with tape.

 

[chimpy]

Hopefully this will fix your CEL problem. I am now in search of the elusive P0440 and P0442 DTCs. The replacement valve at the canister apparently extinguished the P0446 code for me but to have these 2 new codes come up now is really baffling. I asked my local Toyota dealer if they do the smoke test, they do but it will cost $130. It may come to that.
Good luck with your repair and keep us posted.:driving:

 

[Bigmd]

Well doubtful now this is the fix. I just battery tested the old one from canister and it was clicking. So wasted money.

 

[AZBub]

If you have replaced every vacuum line, every VCV, the gas cap and checked the can for cracks there could be the slight possibility you have fuel in the vapor can from topping off your fuel tank too much.

If you are absolutely certain there is no liquid fuel in the can then just JB weld the seam around it anyways. I'm telling you, a pin hole in that can will throw a code. If you are absolutely certain there is not a crack in your can JB weld the seam anyway.

If you followed every step exactly from where I posted the link on the first page the only thing left I could think of is the vapor line from the fuel tank.

I learned my lesson about buying new switches without testing them, that's why I posted about the 9v. Could have saved your money at my expense.

 

[Bigmd]

Thanks AZ. Went back under and jb welded seem. Checked my connections again and even used hose clamps. I'm confident the canister is good now. I never top my tank off because I hardly fill it. I can tell u there is t a hint of gas odor coming from the canister. I have t cleared the code yet so we shall see next few days

 

[AZBub]

Thanks AZ. Went back under and jb welded seem. Checked my connections again and even used hose clamps. I'm confident the canister is good now. I never top my tank off because I hardly fill it. I can tell u there is t a hint of gas odor coming from the canister. I have t cleared the code yet so we shall see next few days

ALL these cans will smell of fuel because thats what it does, filters the vapors from being released into the air.

Most of us are guys so outside of our control we tend to want to sniff everything without thinking about what we are doing...

I sure hope you get it sorted out, sounds like 90% is new or in working order.

 

[Bigmd]

Well something truly miraculous has happened. All lights went off on there own. Shocking , just noticed. I believe it was the loos hose at the canister. Good news is I have all new evap system haha