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1999 Corolla - Po446


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#1 Metrolens

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Posted 21 June 2010 - 03:07 PM

Our 1999 Corolla LE, 122k miles, got a check engine light with a PO446 code. I've tried to read up on these forums, and have found I'm very much not alone.

Facts:
1. I bought a new gas cap, didn't resolve issue. I had the CEL shut off by a mechanic, but it came back on within a few miles of driving.
2. I usually topped off the gas tank, so the canister may be ruined. Won't be doing that anymore.
3. A mechanic ran diagnostics and reported two problems: rear EVAP solenoid, and the vapor canister. The solenoid was apparently "reporting 40" (or maybe it was .40). To repair, he would charge $150 labor, ~$100 for the solenoid, and ~$250 for the canister. (Ouch.) He suggested to fix the solenoid first, and leave the canister alone for now, in the hopes that this will solve the problem and I won't have to replace the canister.


My questions:
1. Fair prices for parts and labor? Is there a good website I should check for parts?
2. Is this even a necessary repair? Is it in any way a safety issue, or will it hurt the car? (I haven't noticed any degradation in the performance of the car. Next emissions test isn't due until 4/2011.)
3. Should I get in touch with Toyota? I'm aware of the EPA recall that affected 1996-1998 Corollas, but apparently the problem has continued beyond 1999 models. This is ridiculous; these cars have a design flaw that Toyota should pay to fix.
4. I've read reports of the CEL shutting off by itself after several gas cycles. Does the canister have the ability to "dry itself out" and perform normally again? One poster said he ran the tank near empty, then filled to only 3/4 full, and repeated this several times... and the CEL went off by itself and hasn't returned, without replacing the canister. Thoughts?

Thanks in advance.

#2 Metrolens

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Posted 22 June 2010 - 01:40 PM

Can anyone chime in with wisdom on this? I need to make a decision about what to do.

#3 fishexpo101

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Posted 24 June 2010 - 10:38 AM

Parts price is about ballpark - labor is what will get you with this system. To check prices - try www.1sttoyotaparts.com or www.rockauto.com - two sites that some posters on here had good luck with.

As for car operation - the EVAP is solely for emissions, doesn't hurt the car at all. Its job is to capture and hold onto fuel vapors that might otherwise be vented into the atmosphere to be burned during normal operation. Only thing that will let you know that you have an EVAP issue is the CEL and possible gasoline odor close to the tank. Performance of the engine will be unchanged in most cases. If money is tight, you could let this go until before you need the car smogged. In most areas, resetting the CEL before you go in is not good enough - you need the onboard I/M fields to be set to PASS. Otherwise, it will be an automatic failure.

As for the EPA recalls, I don't recollect anything that affected Corollas in that generation - the 9th gen had issues with the catalytic converter, the earlier generations had TSBs that involved the EGR system, O2 sensor, and MAP - which mainly centered around the Toyota Tercel.

CEL will shut itself off, not because it "fixed" itself, but because the I/M system didn't detect an issue or the problem didn't exceed a predetermined threshold. Those CELs are still stored in the engine computer - just the light is not necessary illuminated. The VSV valves themselves have the feature of intermittently sticking and unsticking - this can cause the CEL to come and go at seemingly random intervals.

Overfilling the tank (topping off) - probably increased the chance of flooding the vapor canister - it some cases, it will eventually dry out, but the activated charcoal inside will be permantly damaged (canister will not hold gasoline vapors like it did before).

#4 Metrolens

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Posted 24 June 2010 - 11:22 AM

Thanks fishexpo. That is extremely helpful info.

So does it make sense to fix the solenoid now, as the mechanic suggests, and see if that somehow solves the problem? That would at least save us the cost of the canister (which I understand will most likely not "heal" itself, so we would eventually have to do the full repair if we hope to pass the next emissions test, right?).

#5 Metrolens

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Posted 21 January 2011 - 04:47 AM

Hi all, reposting on this topic after a long break, as I'm getting close to having to do this repair for upcoming smogging. Our CEL never did turn off, but the car has been running fine.

Two more questions:

1. Is there any reason to take my Corolla to a Toyota dealer, and ask them to cover the repair? To me, this seems like a pretty bad design flaw. Worth a shot? Maybe I could buy the vapor canister, and ask them to install it for free?

2. Is the following website a reputable place for parts? They apparently have a 1999 Corolla vapor canister on sale for $194, which seems quite a good deal.
http://www.dealerdir...6-corolla-4.htm

Edited by Metrolens, 21 January 2011 - 04:47 AM.

#6 fishexpo101

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Posted 21 January 2011 - 11:24 AM

Worth a shot to ask the dealership - if they will do anything for you, pretty unlikely - as EVAP related issues are hit or miss on the 8th gen Corollas. Some 8th gen had EVAP CEL come on almost constantly, others never have issues with it.

Just a hair under $200 is a fair price for a brand new vapor canister, I've seen them go from $160-$250 for new ones, list price ranges from $280-$360 for a new one. I'd try getting a used one from a salvage yard to see if the vapor canister was indeed the culprit - hate to see $200 go down the drain if it turns out the original one was still OK.

#7 Metrolens

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Posted 21 January 2011 - 02:04 PM

Worth a shot to ask the dealership - if they will do anything for you, pretty unlikely - as EVAP related issues are hit or miss on the 8th gen Corollas. Some 8th gen had EVAP CEL come on almost constantly, others never have issues with it.

Just a hair under $200 is a fair price for a brand new vapor canister, I've seen them go from $160-$250 for new ones, list price ranges from $280-$360 for a new one. I'd try getting a used one from a salvage yard to see if the vapor canister was indeed the culprit - hate to see $200 go down the drain if it turns out the original one was still OK.


Thanks fishexpo. I called the Toyota dealer, no love. They denied knowledge of the problem, even though there was the EPA recall on 1996-1998 Corollas, and it's been well documented that later models have the exact same problem. Hey, thanks Toyota.

So - I found a salvage yard, which has a 1999 vapor canister for $75, but my mechanic dissuaded me from buying a salvage part, saying it could be defective/depleted, in which case I'd have wasted a bunch of money. The salvage yard said it would be a good working part. Who to trust?

Also, I can't find any ratings/reviews on the website www.dealerdirectparts.com. I called them, and apparently all their parts are OEM from the Toyota factory, not aftermarket. The list price I've seen for a vapor canister is $258, but dealerdirectparts sells it for $194 ("wholesale pricing"). Can anyone verify that they are indeed reputable, should I decide to get a new (not salvage) vapor canister?

#8 fishexpo101

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Posted 21 January 2011 - 04:02 PM

Not sure about www.dealerdirectparts.com - never used them before. I have run across that name on other forums - but no feedback, good or bad, on that site. Price wise, they are cheaper than other well known online retailers - namely, www.1sttoyotaparts.com and www.rockauto.com by at least $30-$50.

As for salvage parts - I do agree that it is hit or miss, sometimes you'll get one that is bad at the yard. Lots of yards have a return period or DOA policy - if you try and part and find out it is bad, you can exchange it for another one or get money back / credit for something else. Unless the mechanic can prove it is a faulty vapor canister - I could not recommend buying a brand new one to "try out". Maybe split the cost with the mechanic - buy the vapor canister, have him install it - if the CEL comes back, have him pay for 1/2 of it. Put your money where your mouth is, in a manner.

I've seen some cases where this CEL is a ECM "wolf" cry. Components are perfectly fine, but the threshold for the ECM gets tripped by peculiar logic condition, sensor threshold. Can't really "test" the ECM, as it is more or less a black box, Toyota doesn't want people to have the tools to look inside the box. Best you can do is verify that the sensors are reading correctly.

#9 Metrolens

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Posted 21 January 2011 - 04:33 PM

Not sure about www.dealerdirectparts.com - never used them before. I have run across that name on other forums - but no feedback, good or bad, on that site. Price wise, they are cheaper than other well known online retailers - namely, www.1sttoyotaparts.com and www.rockauto.com by at least $30-$50.

As for salvage parts - I do agree that it is hit or miss, sometimes you'll get one that is bad at the yard. Lots of yards have a return period or DOA policy - if you try and part and find out it is bad, you can exchange it for another one or get money back / credit for something else. Unless the mechanic can prove it is a faulty vapor canister - I could not recommend buying a brand new one to "try out". Maybe split the cost with the mechanic - buy the vapor canister, have him install it - if the CEL comes back, have him pay for 1/2 of it. Put your money where your mouth is, in a manner.

I've seen some cases where this CEL is a ECM "wolf" cry. Components are perfectly fine, but the threshold for the ECM gets tripped by peculiar logic condition, sensor threshold. Can't really "test" the ECM, as it is more or less a black box, Toyota doesn't want people to have the tools to look inside the box. Best you can do is verify that the sensors are reading correctly.


Thanks again fishexpo, you're extremely helpful.

I called the salvage yard back - they said the vapor canister they have is taken from an accident 1999 Corolla, and that it should be good. They also offered a 30 day guarantee on the part.

Here's why after doing so much research on this, I am led to believe that it is a ruined vapor canister:
-I habitually topped off my tank, really filling it to the brim, over a span of 1.5 years, until the CEL light came on and I learned it was very bad idea to top off.
-The car was always parked on an uneven surface - meaning the passenger side was always a good 6-12 inches lower than the driver's side. So, imagining the physics, this would cause the gas to overflow in the direction of the passenger side of the car, presumably flooding the charcoal canister.
-There is occasionally a faint to moderate gas odor, when starting the car.

Is my logic sound in concluding it's a ruined vapor canister, and not something else?

And, is there any reason that the salvaged vapor canister I mention above should be avoided? Is a 12 year old vapor canister really going to function properly? (The risk is that I will have to spend 2x on labor, if the salvage canister is found to be a no-go).

Finally, is there any risk that dealerdirectparts.com SAYS it is OEM, but will sell me an aftermarket vapor canister? Will I be able to tell for sure if it's a real Toyota part?

Edited by Metrolens, 21 January 2011 - 05:15 PM.

#10 fishexpo101

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Posted 21 January 2011 - 05:48 PM

Vapor canister is closer to the driver's side of the car, so inclined parking space should not be an issue. Topping off can saturate the vapor canister, if done over time, could ruin it. Faint odor of gasoline could be from a bad vapor canister, more likely it is from a clogged or faulty vent on the top of the gas tank. Note that a P0446 could be from the cut-off valve at the top of the tank. You'll have to have the EVAP system pressure tested and smoke tested to find out for sure. If the vapor canister was faulty (leaking, cracked, etc.) that will also show up on a smoke test.

As for a salvage vapor canister being any good or not - as far as age is concerned, a vapor canister is nothing more than a plastic container filled with activated charcoal. Its only purpose is to soak up gasoline fumes when the car is not running, and then slowly bleed them off to be burned during normal operations. I'd take a look at the salvage part before I decide to spring for a new one. If the salvage part is obviously damaged, heavily corroded valves, etc. - then I'd pass and lean toward getting a new one. I just hate to see someone spend hundreds of dollars on a "fix" only to have the CEL pop up in their face in a couple of weeks/months time.

My own P0446 issues cropped up at the 30K mile mark - not covered under warranty due to suspected abuse of the system!!?? Anyways, after every dealership and independent shop was adamant of it being a damaged vapor canister - one technician at a new dealership took 2 hours to smoke and pressure check the system - turns out it was the cut-off valve at the top of the tank. Cost was little over $300 in labor, but talking it over with the tech, he printed out an exploded diagram of the component, and hooked me up with the $30 part. Took about 3 hours of work, most of it was with figuring out how to drop the tank without killing myself - swapped the rubber valve and was good up until a couple years ago. At the time I replaced the cutoff valve, I noticed the fill valve was also showing signs of deterioration - now kicking myself for not hitting that as well.

#11 Metrolens

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Posted 21 January 2011 - 05:55 PM

Finally, is there any risk that dealerdirectparts.com SAYS it is OEM, but will sell me an aftermarket vapor canister? Will I be able to tell for sure if it's a real Toyota part?


Thanks fishexpo. Any further advice on the question above?

#12 doubletrouble

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Posted 22 January 2011 - 12:16 PM

a real dealer part will normally have toyota and the part number stamped on the part. A dealer who sells oem parts will sell you a real one. They are usually pretty reputable.
Remember that a lot of times the canister itself is not bad , it is the line"s" or valves are cracked and the mechanic will find out during the replacement , replace the cracked line and canister and of course charge for both. Some will go so far as to not tell the customer about the line and and just replace both and it IS best to replace both anyway if you warranty your work. The only way to tell a cracked line is a smoke test and sometimes even those don't work. It depends on where the crack is.
This comes from my friend the 25 year mechanic now working for Toyota. He says that it is hard to justify a $500-1000 bill without a canister replacement anyway especially a warranty repair. He prides himself in not having come backs and some times you have to replace more parts than you would if it was your own car. Some evap code diagnosis do take 2-4 hours. At $100 an hour it adds up fast.
Myself , I would have a good independent tech do a smoke test first before you let loose on replacing parts. My sienna would get an evap code periodically and the canister would dry out and the code would disappear for a year.
If the system checks out good , go with a junkyard part.

#13 Metrolens

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Posted 23 January 2011 - 02:47 PM

a real dealer part will normally have toyota and the part number stamped on the part. A dealer who sells oem parts will sell you a real one. They are usually pretty reputable.
Remember that a lot of times the canister itself is not bad , it is the line"s" or valves are cracked and the mechanic will find out during the replacement , replace the cracked line and canister and of course charge for both. Some will go so far as to not tell the customer about the line and and just replace both and it IS best to replace both anyway if you warranty your work. The only way to tell a cracked line is a smoke test and sometimes even those don't work. It depends on where the crack is.
This comes from my friend the 25 year mechanic now working for Toyota. He says that it is hard to justify a $500-1000 bill without a canister replacement anyway especially a warranty repair. He prides himself in not having come backs and some times you have to replace more parts than you would if it was your own car. Some evap code diagnosis do take 2-4 hours. At $100 an hour it adds up fast.
Myself , I would have a good independent tech do a smoke test first before you let loose on replacing parts. My sienna would get an evap code periodically and the canister would dry out and the code would disappear for a year.
If the system checks out good , go with a junkyard part.


Thanks doubletrouble.

I seem to recall my mechanic did do a smoke test months ago, and found the hoses and valves were ok, leading him to conclude it was the solenoid and/or vapor canister. Does this conclusion make sense ONLY if he did in fact do the smoke test? (I'm trying to piece together for sure whether or not he did it).

And, given the tricky nature of this error code, doesn't it make sense for me to just bite the bullet and get a NEW vapor canister, thus removing any possibility that a salvage one would be defective and need to be removed/replaced? If I put a salvage one in, and the error code doesn't go away because it is a bad canister, I imagine this would throw the troubleshooting logic way off. Not to mention the 2x labor cost? What I'm saying is, in a way, a new canister costing $125 more than a salvage one could be seen as a form of insurance against this kind of problem from occurring. What do you guys think?

#14 doubletrouble

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Posted 23 January 2011 - 08:20 PM

you are probably right if the new can is only $125 more. I am used to dealer pricing where it could be 10 times salvage prices. . I like your logic. If you had a smoke test than you are probably good to go. Spend the cash on the valve and new can , and be done. ... or just let it go and put tape in front of the bulb.... The Al Gore light is worthless.

#15 fishexpo101

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Posted 24 January 2011 - 09:26 AM

The smoke test is a static process - it should be able to catch 95% of the culprits out there. The issue comes from the other 5%, where it really is a bad hose or connection, just doesn't show up on a smoke test.

I'd say it would be your call on this - there are advantages and disadvantages on getting a new one vs a salvaged part. I'd double check to make sure that you've exhausted all the testing that can be done. There are diagnostic tests that can be done to completely bypass the vapor canister and see if it is truely the culprit. Most of the time, it is the solenoid, that is the trouble maker. I know if it was my car - if I dumped $200-$300 onto a "possible" fix only to have the CEL stare back at me - I'd probably flip out.