DTC PO446

ESOX · Post by **ESOX** » Sat Jun 16, 2007 6:41 am

This trouble code showed up today. The tool said EVAP Emission Control System Vent Circuit Malf. Does anyone know what I need to fix to make this trouble code go away.

It also should trouble code PO 102, But I changed the Mass Air Flow sensor a few months ago, so I dont think the MAF sensor should be causing the problem.

Any advice woould be appreciated.

Thanks MIKE

Post by **HenryJ** » Sat Jun 16, 2007 8:41 am

GM data wrote:Conditions for Setting the DTC

Important

This DTC does not report a first failed test. A first fail of this DTC will have a scan tool status as Not Run.

* The EVAP vacuum decay rate is more than a predetermined value.
* The conditions are present for more than 2 seconds.

OR

* The vacuum present in the EVAP system is more than a predetermined value.
* The conditions are present for more than 4 seconds.

Perform a physical inspection of the EVAP system. Inspect for the following conditions:

* A loose, missing, defective, or incorrect fuel tank cap
* Incorrectly routed or defective EVAP system vacuum and vapor lines
* A malfunctioning or damaged vapor canister
* Charcoal release from the vapor canister

It is possible that you could have a solenoid failing. I have found that the tank valve and purge solenoids can take on dirt and fail.

Rusty Shackleford · Post by **Rusty Shackleford** » Mon Jun 18, 2007 3:15 am

Had one of those at work last week...evap vent solenoid was stuck open. The part isnt expensive and is easy to replace.