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Discussion Starter #1
I have a 2000 Avalon with 110,000 miles on it. The check engine light is on and the error code is P0440. This means that the computer isn't able to bring the vacuum in the EVAP system up to a normal level which means it may have a large leak in the EVAP system. I'm wondering if someone might know a common problem with this code P0440. I've done some research, and it seems that the VSV CCV solenoid could be a common failure.

Also, I wonder if somebody could explain how this system works according to the diagram below. I don't understand why this system has 3 valves. It seems to me it should only have 2 valves--one to stop air intake during vacuum test and one to purge the charcoal canister.

The VSV for EVAP is the purge valve from the charcoal cannister?
The VSV for pressure switching is the stop valve for air intake?
What is the purpose of the VSV value for closed canister?

Thanks for any answers you might be able to help me with.

 

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Well here are a couple of great diagrams I found on Toyota Nation thanks to poster csaxon from 2006. It looks like the VSV Canister Closed Valve is the valve that switches off the air intake for a vacuum test. The VSV Evap is the purge line. I'm still not quite clear on what the VSV pressure switching valve does, but it is located on the canister. The other 2 valves are under the hood. I guess I'll test them with a 9 volt battery to make sure they are working and listen for the click of the solenoid. I'd like to check the pressure sensor for about 1.5VDC with no vacuum and the filler cap off. Anybody know where the best place is to test it? Can I get right on the sensor itself under the car? Thanks.





 

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I think the pressure switching valve is actually to vent excessive pressure if triggered by the vapor pressure sensor. It does not allow air to flow through it unless it is powered.

The CCV valve I believe helps to maintain a vacuum in the evap canister and the fuel tank. I believe it opens to allow air inlet if the canister is actively purging. Then it closes just before the canister stops purging so there's a bit of vacuum in the system.

The CCV valve is the one that most likely has failed.
 

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Discussion Starter #5
I think the pressure switching valve is actually to vent excessive pressure if triggered by the vapor pressure sensor. It does not allow air to flow through it unless it is powered.

The CCV valve I believe helps to maintain a vacuum in the evap canister and the fuel tank. I believe it opens to allow air inlet if the canister is actively purging. Then it closes just before the canister stops purging so there's a bit of vacuum in the system.

The CCV valve is the one that most likely has failed.
Thanks for the info. I did read somewhere though that with the gas cap off the reading should be 1.3 to 1.7 volts.

Here are the steps I plan to take:

1. Gas cap has already been replaced with Toyota OEM.
2. The car has been driven for over a week and the Check Engine light is still one.
3. I plan to take to Autozone and have them clear the code or disconnect the battery and reset it this way. I don't want to do that because the doors will start to automatically lock after I reconnect the battery.
4. I think I will check both VSV valves under the hood with a 9 volt battery and especially the CCV valve.
5. I'll check the voltage on the tank pressure sensor if I can get on it under the car with my multimeter.
6. Check to make sure the little hose has not come off the air filter that goes to one side of the CCV VSV. At least I think it goes there.

If all this checks out, I guess the next best thing will be to have a smoke test done. I'm not going to shotgun this problem. Thanks for your help.
 

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Hold up, have you even replaced the CCV valve yet? You should do that first before anything else. If you have successfully fixed the problem, the check engine light will go out on it's own. The ECU periodically checks the operation and if it's as expected, on several occasions, it will terminate the check engine light.
 

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Discussion Starter #7
No, I haven't replaced the CCV valve yet. I guess that wouldn't be a bad place to start because it's fairly inexpensive and looks easy to replace. I wish I could access that indentifix service and see what the most common failure is for P0440.
 

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Good luck. The system is ridiculous. Toyotas seem to have a more problems with it than other cars. Most common failures are fuel caps and carbon canisters. It is a waste of time to just try and replace a vapor pressure sensor or, VSV as they come with the canister assembly. The non replaceable vent valves on the canister fail and leak. Have replaced lots of canisters and fuel caps. Hardly any CCVs or purge valves. If you live in the salt belt look for rusted hard lines in the system.
 

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Discussion Starter #9
Good luck. The system is ridiculous. Toyotas seem to have a more problems with it than other cars. Most common failures are fuel caps and carbon canisters. It is a waste of time to just try and replace a vapor pressure sensor or, VSV as they come with the canister assembly. The non replaceable vent valves on the canister fail and leak. Have replaced lots of canisters and fuel caps. Hardly any CCVs or purge valves. If you live in the salt belt look for rusted hard lines in the system.
Thank you for that info. Do you know if I have to drop the muffler to replace the canister on a 2000 Avalon? Is it something your Joe Average shadtree mechanic could do?
 

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Hi,

I am getting the same error code...along with P0441 and P0446
Please can you advice how much would the dealership charge if I go to them?

Thanks,
Ash
 

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Endzone, are you still working this problem? I have a 2000 with the engine light on and I cannot hear the normal air rush when taking the gas cap off. I plan on putting a variable resistor in place of the vacuum pressure sensor, setting the voltage to 3.3 and making sure the engine light goes out with this setup. Then I want to pressure test the tank and look for leaks. I do live in the salt belt and the metal pipes are rusty.
Comments are welcome, let me know how you progress.
 

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Here is what someone posted on the 440 problem:


code mystery solved
Thought I would share my experience tracking down root cause of this code.

P0440 = vacuum leak

There are many place to look.
1. I replaced all suspect hoses
2. checked all vacuum actuators with mityvac (they should all hold a vacuum, if not their junk)
3. checked all vsvs for proper operation 4 of these on car up front. 1 mounted on backside of air cleaner cleaner (normally open), 2 near fuel rail (2 the same type normally open), 3rd was suspect (should be normally closed [it is blue])
4. to fix the blue vsv I simply disasembled it and gave the spring a bit of a stretch. then reassembled and it worked like a charm.
5. The is another vsv located on the right side of the charcoal canister (located between gas tank and spare tire) This vsv also proved to be suspect testing with mityvac.

Replacing the rear vsv and fixing the blue vsv, solved the issue.

Note to test these use 2 wires and a switch from the battery, then connect wires to the vsvs.

The brown and black vsvs will not completely hold a vacuum the others will. the brown black simpley divert air either through the round barrel like fiter on the end or to the output tube. The blue vsv, the one mounted to air cleaner and the one on the charcoal canister all hold vacuum when being tested.

Hope that helps someone.

You can also do a search for 'P0440 and vsv" for more info on Toyotanation.
I have had the P0440 problem on two of my cars and I have installed the VSV near the cannister where it is only one bolt or nut and looking right at you. I think the part was $70 at the dealer. I am assuming your gas cap is a Toyota product.
 

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Here is what someone posted on the 440 problem:


code mystery solved
Thought I would share my experience tracking down root cause of this code.

P0440 = vacuum leak

There are many place to look.
1. I replaced all suspect hoses
2. checked all vacuum actuators with mityvac (they should all hold a vacuum, if not their junk)
3. checked all vsvs for proper operation 4 of these on car up front. 1 mounted on backside of air cleaner cleaner (normally open), 2 near fuel rail (2 the same type normally open), 3rd was suspect (should be normally closed [it is blue])
4. to fix the blue vsv I simply disasembled it and gave the spring a bit of a stretch. then reassembled and it worked like a charm.
5. The is another vsv located on the right side of the charcoal canister (located between gas tank and spare tire) This vsv also proved to be suspect testing with mityvac.

Replacing the rear vsv and fixing the blue vsv, solved the issue.

Note to test these use 2 wires and a switch from the battery, then connect wires to the vsvs.

The brown and black vsvs will not completely hold a vacuum the others will. the brown black simpley divert air either through the round barrel like fiter on the end or to the output tube. The blue vsv, the one mounted to air cleaner and the one on the charcoal canister all hold vacuum when being tested.

Hope that helps someone.

You can also do a search for 'P0440 and vsv" for more info on Toyotanation.
I have had the P0440 problem on two of my cars and I have installed the VSV near the cannister where it is only one bolt or nut and looking right at you. I think the part was $70 at the dealer. I am assuming your gas cap is a Toyota product.
I've replaced the charcoal canister and the CCV. The check engine light comes back 1 month later with three codes, 0440,0441,0446. Which blue vsv are you talking about? Do you have a pic?
 

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I took pictures of the part, but I can not upload it to Toyotantion due to its size.
If you want to send me your e-mail I can send the pictures to you.
 

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I looked at the upload site. I do not want to register and receive more random e-mails solicitations from the site. You have my e-mail address if you want to pursue the pictures.
 

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Had a P0440 that would come back every time I cleared it, on a 01 Avalon. Sent direct battery power to the two VSV's under the hood and the one VSV under the car at the back, to make sure they were clicking and not stuck. I must have had one that was sticking, because the code is now gone for good
 
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