P0446 Error

I thought I would take a moment a share my issue and resolution encase it helps someone in the future.

About a month ago I starting get a "Pending Code" on my Ultra Guage, P0446. Then a week later my check engine light came on, same code. I grabbed a new Toyota Fuel cap, didn't help. Every time I started my truck I got the code, even reset it a few time, nope still got it.

Well, as life was happening I didn't have time to start troubleshooting.

Then, I started noticing my battery going, slow starts, that sort of thing. Still getting the P0446 code. Finally, battery dies, after installing the new battery, no more code.

I am assuming that the computer starts doing the POST test off of the battery before the engine is started. With a dead battery, or almost dead, than there was not enough power getting to the VSV solenoids to complete a proper test, thus causing the code.