I know this is an older thread, but looking for some info.
I'm throwing the same code p0446. I've been testing the voltage at the rear charcoal canister VSV and I'm only getting 2.6v unlike the 12v on the other two vsv valves in the engine bay when the ignition is on. Is that normal voltage, or is that my issue?
I believe the vapor pressure sensor (the one that has only 1 hose coming off it) is a 5v part.
Here's a link that might be helpful in tshooting this issue. EVAP Tshooting
Thanks