P0446/P0440/P0441

I am driving first car(Toyota corolla LE- year 2001, 42000 miles) of my life and today morning It failed road side inspection. The error code given are

1) P0446 : Evaporative Emission control system Vent control circuit
2) P0441 : Evaporative emission control system incorrect purge flow
3) P0440 : Evaporative emission control system

It would be greatttttttttly appreciated if someone can guide me what needs to be done/changed to fix these codes. Thanking you in advance.

look for a disconnectted or damaged hose around the air filter box that goes the evap solenoid, sometimes it's gets knocked off when servicing the air filter, solenoid could be failled, the cannister could be breaking down and causing the evap solenoids and valves to stick. can be a trickier system to diag because there are lots of components in the system

good luck and keep us postted

Hope this helped

Jeff

Jeff,
thanks for your reply. As I am new with car,I couldn't locate airfilter .With my friends' hlep we checked hoses around airfilter. nothing obviously craked there.I had gas tank overfilled last time. I let that gas run out and filled new gas at 3/4 tank full. I haven'r reset codes by pulling negative of battery. What would be your suggestions to proceed ? can cannister die after 42000 miles ? My car was salvaged and refurbished and I am NOT the first owner of the car. Does totyota dealer warrenty hold good for Emission for this kind of case ?How can i make my self familiar with different internal parts like cannister and EVAP system parts ? expecing great help.
thanking you,
coolstuf294

cannister failure could occur at 42 OOO miles, especailly if the tank is overfilled alot, If the car has been salvaged then look for a damaged hose around all the components or the cannister itself may have been damaged and or replaced with a used part. I'd recommend buying a chilton manual for your car to better familarize yourself with the systems but unless you don't see an obvious damaged hose or something then see a good technician with a smoke machine for diagging evap leaks

good luck and keep us postted

Jeff

Don't know whether you got your problem resolved but I have a 2001 Corolla approx 43K miles and have the same codes. Dealer says one of the pruge valves near the charcoal canister was defective. There are two valves involved at the canister. They run about $50 but it's the labor that will kill you.

i work for a lexus dealer which is basically a glorified toyota. any time the three codes come on together it needs a charcoal canister. the valves are part of the canister

cmonster- thanx for the scoop. is there a way to test the cannister. I have an 01 Highlander (6 cyl) and an 02 RX300 and both have these three codes. They reoccur about every 300 to 500 miles after the reset procedure seemingly irregardless of driving or ambient conditions. The Highlander has about 140k miles, the RX about 72k.
Also, the Highlander has a code (I forget the P number) for evap control solenoid.

TIA
Mark

The most accurate way to test both systems is with an smoke machine that pressurizes the evap systems with a chemical smoke that helps pinpoint leaks, valves can be checked with a dvom and a vacuum pump.
Deteriorated cannisters will cause repaet valve failures. Cannisters and valves often fail from overfilling gas tank. The raw fuel floods the filter material and causes it to break down.

I have a '98 Toyota Corolla with these 2 codes coming up now.

P0441 - EVAP emission Control System Purge Flow Fault
P0446 - EVAP emission Control System Vent Circuit Malf

I've replaced the gas cap so far. I still have yet to check some other suggestions (air filter leaks, etc) I recently changed the spark plugs and wires.

Another symptom is that the gas mileage has dropped from its usual 35-36 mpg down to about 31 mpg.

From other posts it looks like a good possibility that the canister could be bad. Where is this piece physically located in the car? if it had to be replaced, would an amateur DIY mechanic be able to handle it?

Thanks in advance for any tips, suggestions.

Paul

all depends on how the amateur mechanic is equipped and how competent they are! Do you own a manual for the car?

Nope, don't have a manual yet. Cheapskate that I am, I checked the local library last night to see if they had a Chilton's or Haynes manual; they didn't.

Toyota sells a shop manual for about $50; I've considered getting that one.

I checked the air filter connections this morning and didn't find anything loose.

Where is this canister part located? How extensive of an operation is it to change the part?

Paul

autozone might print out pages from ALLDATA

Hey guys,

I found this pic on another post somewhere, I have a 98 Corolla VE with a P0441 problem. I *believe* this pic is for a Corolla.




I've been driving around with the check engine light on, but if another code should happen other than the evap system, I'll never know about it. Nor do I have $400 to go to the local Toyota dealer to have them diag the problem, even though I can already give them the code.. then the canister/valve unit is $300.. argh..

good luck with yours!

98CorollaVE

Friends,
As per following link, replacing VSV can fix P0446

http://www.corolland.com/forums/lofiver ... 17838.html

Three common problems and fixes for the 2001 Corolla

This post is intended for those who have only basic tools and knowledge. Obviously, you need a scan tool to get the trouble codes, if you don't have one, get one, it will quickly pay for itself.

Here's what Carfax says about the '01 Corolla:



Somehow I think the above repairs would be more expensive in the real world. If anyone had these done by a dealer, I'd be curious to know what it cost, just to see how much money I saved.

I have had both the VSV problem and the MAF problem (occurred at separate times). Below is how to fix them. These are very common problems for this vintage of Corolla and other Toyotas that use the same technology.

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.

Mass Air Flow (MAF) - Code P0171 (system running too lean)
This also does not affect driveability (unless you're an aggressive type) and you might find your fuel economy actually improves (I did). I presume Toyota designers had their reasons for not having this as a normal operating condition. Anyway this problem is very easy to fix. The MAF determines how much air for combustion is being sucked in by your engine at any given moment, which is important for setting the appropriate fuel-air ratio. What happens is that over time, the sensing elements in the MAF get coated with black goo from all the air that is going through them. It is located under the hood and is installed on the intake air filter housing. Undo the electrical connector, and it is removed from the air filter housing by uncrewing two Phillips screws. Very simple, takes 5 minutes. There are two sensing elements, one is in plain view, the other is concealed in an air channel and much smaller. You can see the smaller one by looking down the channel. It looks like two small beads, each suspended on two wires. Just spray a solvent on them to clean them off. You will see the black goo visibly get washed away. I used disc brake cleaner, which is just isopropyl alcohol with a propellant. Do not use WD-40 or similar lubricating products because they leave an oily residue. Put it back in, reconnect the electrical, reset the CEL, and you're done!

Here is a photo of the MAF. It's for a Tacoma/4Runner but as I said, the technology is the same (the sensor is identical).



So far I haven't had the third common problem mentioned above (Pressure Sensor Vacuum Switching Valve), I imagine it's a similar process to the VSV replacement, since it is located right beside the VSV.