P0446/P0440/P0441

I cleared the codes and drove the car again. The MIL came back on in about a day but only with 441 and 446. Would it be safe to say it is the canister or not? Rotten Emissions test tax...

No, clearing the code isn't fixing it. Quit trying to cheat the emissions test and fix the car or pay someone to fix it!

Ehh... Jeff, I think you spouted off before you read the post. So I will paste it here for you to read once more..

"I cleared the codes and drove the car again. The MIL came back on in about a day but only with 441 and 446. Would it be safe to say it is the canister or not? Rotten Emissions test tax..."

Now, what part of that led you to believe that:
1. I thought clearing the code would fix it???
2. I was trying to clear the codes for the sake of cheating the Emissions Tax???

I am trying to see if there is a concensus or not that the canister is to blame.

Without the car in front of me to test it's not safe to say that the cannister is rotten and the cause of the codes! My post says fix the car or pay someone to fix it! Test the vlaves and solenoids for the evap system or replace them as a guess or pay a shop to do it! That's what my post says!
My crystal ball and magic 8 ball are on loan to the kids at Autozone so it's not safe to say anything without seeing the car! Yes you're cannister could be bad but it also might not be! If I say it's likely and you change it and it's still broke then we both look foolish right!

Good grief Jeff. Your post also says "quit trying to cheat the emissions test."

I never asked for crystal ball answers, just whether or not there was a concensus as to the canister being the cause. Please reread once again Jeff. If you are a mechanic you yourself I am sure have replaced parts with only a 90%+ certainty as to the cause, if you are honest...

I would prefer you not respond to my posts any more as this is leaving the land of rational and reasoning discussions.

Okay then yes the cannister is rotten, change it! I think that's the answer and magic bullet you seek! Don't ever assume that you know anything about how I do my job or what kind of success and certainty I have when I do it. Okay so you don't want to cheat the emissions test. Fine but clearing the dtcs and freeze frame data when you clear it erases valuable information that professional techs use to troubleshoot the code. should you ever break down and decide to take your car to one. Often those cars have cannister failures which cause valves and solenoids to stick which is why I suggest checking or replacing them first because they're likley less costly but throw the cannister in first if that's what your heart is set on. Other sites on the net dedicated to toyota's would verify what I said. You might find other Toyota owners to be more of an expert then a bunch of technicians on a site like this one.

I pulled a 2001 canister system (with valves) off of a car and am trying to fit it to my 1999 Prizm, but the 01 has an extra hose coming off of the Vapor Pressure Sensor. Does anyone know how to connect this system up to my 99 or have a diagram of the 2001 evap system for a Corolla?

sigh. Is it really so expensive? The reason the Prizm has one less hose may be because of enhanced EVAP systems on newer autos. THere's a vent solenoid rather than just a vent. As to how to install a toyos canister on a prism? I'd have to ahve it in front of me and I'd need to be on an episode of junkyard wars.

I loved Junkyard wars! Are the proper parts really that expensive!

A big thanks to corolla2001 for the wealth of information on the Toyota
Corolla VSV problems leading to P0441/P0446 codes. I have a 1998 Corolla
that developed these codes. (You can get a very nice code scanner,
Actron PocketScanner from http://www.tooldiscounter.com, Part No. ACTCP9125, for
only $44.00 plus shipping.) First as a warm-up exercise, I checked the
purge valve VSV under the hood (the one that is easy to get to but hardly
ever goes bad). I found that when I removed the electrical connector and
applied 12V, an audible "click" could be heard and air passage (by blowing
through) went from closed to open, as it should. So next, I went
underneath the rear end by the gas tank to investigate the pressure sensor
VSV on the charcoal cannister. By removing some hoses I could get to the
electrical connector and did the same thing as I did testing the one under
the hood. Although the coil resistance was withing specs (about 40 ohms) and
it drew current, I did not get a "click" like the one under the hood. So I
proceeded to remove the VSV, did "much cursing while attempting to remove
screw," as corolla2001 says, and got it out. (His suggestion to use mini
vicegrips to break the screw loose worked good.) So the next day I called
a Toyota dealer for a replacement, but was told that they don't make this
valve any more and I would have to replace the entire canister assembly
which includes the VSV, at a cost of about $300 and which requires removal
of the muffler - ugh!. Not to be deterred, I called another dealer and
with the VIN was able to get the part number (9091012267); they didn't have
it in stock (sold the last one a couple of days earlier!) but could order for
$88. I then called back the first dealer and asked them to look up the
part number, and to my surprise they had one in stock and would cost $74
(after telling me earlier that I could not get it)! So I picked one up and
put it in. Again, corolla2001 was absolutely right that it is impossible
to replace that single screw that holds it to the bracket (although I
valiantly tried every trick in the book for almost an hour!), but the
attaching hoses offer some support and to make sure, I took his suggestion
to firmly hold it in place using a cable tie so that repeated movement
would not eventually cause the electrical wire to break. So, after all
this, good news - the CEL is off and stayed off!

Hooray!

HI....

Well,, I think the main problem is in the EVAP VENT VALVE, you should first check the vent valve and then afterthese check, you will determine if it was the cause of the bad purge flow or in the otherhand, was caused because a broken hose, leakage etc..
But first, just check the VENT VALVE....
For me sounds that it is only the VENT VALVE...¡¡¡¡

I have a same problem with my RX300. After replaced a canister now the CEL seem doesn't go away. It might be a VSV problem. If anyone own a RX300 or know a how to fix this problem, I would like to hear for you.

Forgive the newb question, but what are the potential long-term effects on the vehicle if a failed evap vent valve is left unreplaced?

If the vent valve is faulty there will be no long term effects on your ENGINE, however your EVAP system won't operate properly, raising your emissions.