S14; trouble code P0446

M

Michael.Timz

Member
i've had this code come up before, but it went away after i plugged a disconnected EVAP hose back in.. that hose is still connected, so i'm stumped.

anybody else ever gotten this code and/or knows how to fix the problem?

the auto-zone receipt that the guy printed out for me says:
"The PCM has determined that a malfunction exists in the electrical circuit for the vent control in the evaporative emission control system"

i don't know if this is a generic definition for any EVAP system malfunction or what.
the gas cap is on tight, and as far as i can see, all the EVAP hoses are connected.

if the chilton's repair manual wasn't so damn vague on the location of the charcoal canister, i'd have checked that too.
 
ok there is a Vacumn Switching valve (VSV), its a valve that is controlled electronically to vent pressures in the EVAP system, when it gets stuck it throws that code, you have to replace that vsv or replace the whole carbon canister, ussually the carbon canister failes and fuel is allowed to enter into the canister and messes up the VSV.
A quick check is to make sure the VSV is getting voltage, or using Consult (Nissan) and manually turning on the VSV to make sure its working, if it dose that, its a 75% chance its the canister(vsv ussually comes with the new canister). the EVAP system is one of the hardest things to diagnose because of how much of a complex system it is, I'm glad i have OBD1 for this, but OBD1 sucks for DIAGing. Now thers also another VSV located in the somewhere in the engine bay, cant recall where its at on S14s, but check that also.
 
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