2004 Denali P0446 Code

[t2man3591]

I'm having a hard time clearing the 0446 code on my Denali 2004. I have replaced the fuel cap and the Evaporative cannister purge solenoid(3 times with no luck) Any ideas out there?

 

[6speedblazer]

That code is for the vent solenoid, not the purge solenoid.

Purge solenoid is located on the engine; vent solenoid is located on the side of the evap canister. You need to test for power and ground at the vent solenoid plug and run an ohm test on the solenoid as well.

use a bi-directional scanner to turn the vent solenoid on and off when you check for ground. Note the circuit is 12 volt constant and switched ground via the PCM. its pretty common for the wires right at the pigtail to fail internally from stress or corrosion.

 

[Fless]

You can use the diagnostic procedure detailed in the link below, but verify your vehicle info first:

P0446 — 2004 GMC Yukon/Denali 4WD V8-5.3L VIN T Service Manual | Operation CHARM

Detailed repair manual for the 2004 GMC Yukon/Denali 4WD V8-5.3L VIN T.

charm.li

The vent valve should be located above the spare tire; it can be tested on or off the vehicle, but as @6speedblazer suggested, verify that the computer has control for switching.

The vent valve is "normally open," meaning that without 12vDC applied, you should be able to blow through it. When 12vDC is applied (polarity doesn't matter if it's taken out of circuit) the valve should be closed, meaning that air can't flow through it.

Many times the dust filter on or attached to the valve is plugged.

 

[SteveZ]

I'm having a hard time clearing the 0446 code on my Denali 2004. I have replaced the fuel cap and the Evaporative cannister purge solenoid(3 times with no luck) Any ideas out there?

Solved mine replacing fuel pressure sensor on top of tank at fuel pump. Used short-cut access under back seat.