I originally responded to a simlar thread in 3rd Gen, but maybe I shouldn't have hijacked the thread..anyhow...

I'm sure most of you are bored discussing this issue....but I had all three CEL, VSC Trac & VSC Off lights come on together. I took it to Autozone and got the three codes PO440, PO441 & PO446. After searching thru threads, I purchased a new gas cap and reset (disconnected the battery). A day or so later the lights came back on...back to Autozone and only 2 codes PO441 & PO446. I took it into a toyota dealership and they told me I needed a new charcoal canister $600+. In another thread I found people talking about 2 other solutions I would like to try before spending that cash...replacing the VCV valve is an inexpensive possible fix along with the cleaning of the MAF sensor. Does anyone have pics of where these two items are located? Thanks in advance for any help.

Bump...I disconnected my battery to reset when I originally posted this thread...the lights have not come back on. Am I fixed? or am I running around with a problem? I did nothing to either clean the MAF sensor or replace the VCV valve. Been two weeks and it just appears to be gone. Anyone got any ideas? I'm worried I'm running around with an issue to only wait and get worse.

If the lights illuminate with the key on prior to engine start you're golden! Each start it goes through a self test and if the dash lights light and then go out all is good.

Thanks CJ3Flyr...I'm unsure just because I did nothing.

The CEL does come on when I turn the key on prior to engine start, then goes out once it starts up. So maybe I am good.

Sounds good, being lucky rather than good isn't always a bad thing