That is an EVAP system code - the car will still run OK, but if you have emissions testing, it will automatically fail due to the CEL. As with most of these type of things, the longer you leave it be, the greater the chance that something worse could pop up.
I'd try resetting the ECM and see if the code comes back - more often than not, it will not return. If you have a habit of topping off the gas tank, stop - there is a good chance that you could flood the vapor canister with fuel. That will cause all sorts of EVAP related problems - some more serious than others.
P0446 - Evarorative Emission Control System Vent Control Circuit Malfunction
P0441 - Evaporative Emission Control System Incorrect Purge Flow
Both refer to an issue with the EVAP system - the P0446 is a more encompassing problem, as it detected a malfunction in the circuit (this case, the whole EVAP system). P0441 is more targeted, but can be related to other issues - as many times both of these code pop up together. P0441 is triggered when the vapor canister cannot keep a vacuum. Usually from leaky hoses, bad valves, cracked canister, etc.
Both of these can come about from a bad gas cap seal (the rubber gasket) and/or topping off the gas tank (a really bad habit).
In either case, check the gas cap's gasket for excessive wear or damage, re-tighten the gas cap - reset ECM. If the code pops back - have the EVAP system "smoke" tested. There, they fill the whole system with a tracer gas or smoke, then use a sensing wand to find any leaks - the fastest way to find these problems. Well worth the diagnostic charge to have this done. Once you have the diagnosis - you can do the repair work yourself and save a bundle of money.
i am one of thoes people that tops off the and then some, i did'nt realize that this would couse a problem. I just filled up last night and now i did'nt put in any more gas once the pump stopped i the reset the computer and so far so good. Thanks for all of your help with this it is really appriciated.
I've topped off for years and I have the Check Engine (CE) light with that code. I've been driving with the CE light on for three years now. Car has not blown up.
I did have the Smog Check issue. Not wanting a auto fail I had the code cleared and then I tested. All OK. I was lucky that after the test the stupid light came back on.
The main EVAP components for the 8th gen Corolla are located under the car, between the rear wheels, just infront of the gas tank.
If you jackup the rear of the car and take a peek underneath - you can't miss them. There are also portions of the EVAP system that sit ontop of the gas tank (have to drop the tank to get to them), vacuum lines also run the length of the car to the induction system (intake manifold, airbox, throttlebody, etc.).
Most EVAP related codes and issues generally won't hurt the car. You may catch a strong gasoline odor from the rear door / gas filler tube area and in area that do the simple I/M emissions testing. A CEL or I/M readiness set to "pending or not ready" is an automatic failure.
My first EVAP CEL was for the cutoff valve on the top of the tank - major PITA. Then after I fixed that and the VSV solenoid on the vapor canister - been getting a CEL only on emission testing years (Yay!) and for some strange coincidence, they seem to occur about a week or two before I plan to bring it in to smog (last time, the CEL came on as the car was drive into the inspection station!). Of course, I have to reset the CEL, drive to set the I/M readiness and then retest. The CEL stays off for two years, until I have to retest for emissions.
thanks for the info, i think my problem was the from me filling up my tank to much. I no longer get that rotten egg smell and the cel has been off for 129 miles now, i was only getting about 80 before.Thanks again for all of your help it looks like you saved me alot of money.
P0446 - Evarorative Emission Control System Vent Control Circuit Malfunction
P0441 - Evaporative Emission Control System Incorrect Purge Flow
Both refer to an issue with the EVAP system - the P0446 is a more encompassing problem, as it detected a malfunction in the circuit (this case, the whole EVAP system). P0441 is more targeted, but can be related to other issues - as many times both of these code pop up together. P0441 is triggered when the vapor canister cannot keep a vacuum. Usually from leaky hoses, bad valves, cracked canister, etc.
Both of these can come about from a bad gas cap seal (the rubber gasket) and/or topping off the gas tank (a really bad habit).
In either case, check the gas cap's gasket for excessive wear or damage, re-tighten the gas cap - reset ECM. If the code pops back - have the EVAP system "smoke" tested. There, they fill the whole system with a tracer gas or smoke, then use a sensing wand to find any leaks - the fastest way to find these problems. Well worth the diagnostic charge to have this done. Once you have the diagnosis - you can do the repair work yourself and save a bundle of money.
I also had P0441 and the problem was a Vacuum Switching Valve , VSV, It cost $80 at dealership. I drive 2002 Corolla w/ 102K milage. Here is how I did it:
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.
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