P0440 & p0441 & p0446

[thrashor]

Hey all,

Need your help to figure out why all of these codes(P0440, p0441, P0446) are happening to my '99 Corolla VE.

It all started about 2 years ago now with just the one code: P0441

Since then (about a year ago) - I changed the entire charcoal vapor chanister with all the attached components... for a wreck with 60,000kms ... and that did not work...

Fast forward a year from then untill now - and the result is as follows:

Hard codes: P0441, P0446

Soft/pending codes: P0440, P0441, P0446

Any idea how to troubleshoot this ?


thanks

[new echo owner]

Have you try a new gas cap? A leaking gas cap will set those codes. And also a leak evap system vent valve will do that too. Try this TSB to see if it will help: http://www.northwestmr2.com/incoming.../Engine/06.pdf

N.E.O.

[thrashor]

Originally Posted by new echo owner

Have you try a new gas cap? A leaking gas cap will set those codes. And also a leak evap system vent valve will do that too. Try this TSB to see if it will help: www.northwestmr2.com/incoming/dutch/Toyota/celica/Service%20Bulletins/Engine/06.pdf

N.E.O.

Thanks so much for the Tech Bulletin - should help very much just a first quick glance as I'll be more than greatfull to try and study it tomrrow.

Shoot - I forgot, yea I did try a new gas cap - well used from a wreck, as well as the working cap from my '95 Toy Avalon - back when the first origional code occured - and that did not work at all -

BUT, that does reimind me to suggest to you that there seems to be a lack of any pressure at all from the fuel tank when I remove the gas cap to refuel ...

[ea8631]

too lazy to type out...

[thrashor]

Originally Posted by new echo owner

And also a leak evap system vent valve will do that too.
N.E.O.

A leaking evap systwm vent valve - could that explain why the no fuel tank pressure when removing the fuel cap?

Thanks again -

[thrashor]

Thanks http://www.toyotanation.com/forum/4263-ea8631.html for the input - most helpful! Looks like I got my work cut out for me with this... lol

[new echo owner]

Originally Posted by thrashor

A leaking evap systwm vent valve - could that explain why the no fuel tank pressure when removing the fuel cap?

Thanks again -

Possible, if it is stuck open!

N.E.O.

[gary1015]

How are you guys! Yesterday i checked on a check engine light and scanner showed 2 codes P0441 and P04469 Evap system purge flow low, and Evap Vent solenoid problem. The shop said that from the beginning i have to replace charcoal canister and further we will see. If anybody familiar with that problem please help. Thank you.

[fishexpo101]

Almost guarantee that the vapor canister is fine, unless you have been topping off the tank frequently (a really bad habit, should not do this). Pretty common codes for an 8th gen Corolla - search the forum for those codes, as there are multiple culprits that can set those codes. The most common is a bad VSV on the vapor (charcoal) canister. Generally gets gummed up or sticks, as it is exposed to the elements constantly. Other causes are leaking vacuum lines and/or faulty electrical connections/wiring to the VSV. About $70 to replace - vs $160-$350 for a vapor canister. Most shops start with that because it is the most expensive part.

[gary1015]

Thank you very much will definitely check it first but do you know if it possible to check VSV sensor on resistance or there is another way to check it before replacing it. Thank you

[fishexpo101]

The VSV acts like switches - under ECM control, opens or closes at predetermined intervals and thresholds. Unfortunately, without the Toyota scan tool, hard to control individually. Without it, you would have to find a way to put 12V on the leads to power the VSV on and off - then verifying that you have flow pass or no pass conditions. Since you have a P0441 and P0446 - could be either a bad VSV or CCV or even both. There is a small chance it could be a cracked vacuum line or bad electrical connection. You can see if the voltage in the source lines is getting to the sensors - but you would need to know the control strategy to figure out which sensor is being powered at what time/under what conditions (hence the Toyota scan tool really helps here). Other than that - you could check for one of the connections to be referenced to ground (chassis). But I wouldn't even try that unless you have a multimeter with pretty high impedance inputs (need good measurement resolution to see values in millivolts).

[dorman68]

My buddy had the same issue on his 2000 Corolla. He needed the VSV or vacuum switching valve next to the vapor canister. The local parts guy stated that this is a fairly common problem.

[yanlapanic]

hi , I had this problem and my mechanic say it was not a big concern and he shut the light off ...

[Radial GT]

Huh, that light comes back on. I tried that

[JohnT106@hotmail.com]

Originally Posted by dorman68

My buddy had the same issue on his 2000 Corolla. He needed the VSV or vacuum switching valve next to the vapor canister. The local parts guy stated that this is a fairly common problem.

Same here. Had a P0441 code, (found out by failing inspection) got a Vacuum Switching Valve ,VSV, for $80 at Toyota Dealship and I was able to clear the light and zip right through inspection. Glad I didn't buy a charcoal canaster for $350. I found these instructions on another post and they worked like a charm.

Vacuum Switching Valve (VSV) - Codes P0440, P0441, P0446
There are two VSVs. One is up at the air cleaner (according to my dealer this one almost never fails) the other one (the one that does fail - wouldn't you know it) is down underneath the car beside the gas tank, and adjacent to the charcoal canister. Presumably it fails because it is more exposed to splash from the road. One clue that it is a problematic VSV is that the above 3 codes appear at the same time. This problem does not affect vehicle driveability, although it might be a problem when you go for your emissions test. Replacing this valve is not hard but it is uncomfortable because you're lying on your back looking up at the VSV (unless of course you have a hoist - which I don't) and dirt is falling on your face. You just have to pull off a short (few inches) length of tubing which obstructs access to the VSV. This tube is not clamped, you just pull it off, it is a larger diameter with a small tube branching off. Once you have pulled that off, you have a better view of the VSV. It is held by one Phillips screw, which is hard to get at. You would need a right-angle screwdriver; I don't, so I just managed to get it off by grabbing it with a pair of pliers, and turning it bit by bit. Narrow vice-grips would be good too. Feel free to do much cursing while attempting to remove screw. When the screw is removed, undo the electrical connector, and pull off the two tubes from the valve. Out with the bad, and in with the good. In my opinion the VSV is held quite firmly by the attached hoses and electrical connector. I didn't try to get that screw back in, it is just not worth the effort. You could use a cable tie to secure the VSV quite well. Reset your CEL and congratulate yourself.