About two weeks ago, while driving on a hot, humid summer night, the check engine light in my 1998 Toyota Corolla came on. The following day, I took it into my mechanic, who plugged it in and came up with the code P0441 (Purge flow fault). He told me it was likely related to the fuel vapor canister, though I see this can also have to do with vacuum lines for the purge valve and canister or a bad purge valve itself. My gas cap was, and had been, tight, so it wasn’t something as simple as that. Unfortunately, the repair bill he quoted me ran $650.
Reluctant to deal with this immediately, I went back to driving it, and lo and behold - the light went off after several days! Unfortunately, the light came BACK ON after several more. And most recently (a few days after coming on again), the light has now gone off!
Both times the light has gone off, the weather has been rather wet, but otherwise, there doesn’t seem to be a clear pattern.
Does anyone have any ideas about what this on again off again pattern might say about the problem???
A few years ago, my 2002 Sienna had intermittent fails in the tank pressure issue. Eventually another man on Sienna Chat had the same problem, but he had two Sienna’s. He swapped the canister assemblies and the problem followed. He fixed it. I took my car to Toyota and had them put in a new canister assembly and haven’t had any problem since.
Note that the code varied from time to time, but all were related to same thing.
If it’s the can it’s gonna be pricey. Extra sad because it’s an emissions component not a performance one. The purge valve could also be the culprit and that will cost $2-3 hundred, but it only needs to be done if your area requires emissions checks. I’d change the gas cap first, also, then look under the hood for loose or damaged hoses in the emissions system. If that stuff doesn’t fix, then you gotta check your purge valve or can. A good mechanic will know which of those two it is prior to replacement.
Again, if it’s the purge valve you will be paying to turn off the light. I’m not sure about the can, it could be just the light but I’ve also heard smart folks suggest it may cause too much fuel to wash your valve train.
Thank you all for the helpful comments - I’ll buy a new gas cap this weekend and see how that goes. If the issue isn’t resolved, I’ll take it back to the mechanic to get a better sense of whether it’s the can or the purge valve, and let you know what happens.
It’s only a problem if you make it a problem…Some charcoal canisters have an air intake filter. If the filter gets clogged, you get the low-flow indication…But it’s not something to lose a lot of sleep over…
So, an update - I replaced the gas cap about 2 weeks ago and thought that had done the trick. As my tank neared empty today, however, the check engine light came back on. Could this have anything to do with there being very little gas in it at the moment and low pressure?