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Paul M ASE Master
Paul M ASE Master, ASE Master Tech
Category: Chevy
Satisfied Customers: 4684
Experience:  ASE Master Tech 20+ Years
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2004 Chevy Tahoe: the engine light came..P0446..probable causes

Customer Question

Hello, I drive a 2004 Chevy Tahoe and the engine light came on, troubleshooting code P0446 and gave probable causes how do I know which is the problem for the engine light to come on
Submitted: 5 years ago.
Category: Chevy
Expert:  Paul M ASE Master replied 5 years ago.

Hello and thank you for using Just Answer

I'm Paul and I will help you with your Question


the only way to know for sure is using a smoke machine to check for leaks and to energize the solenoids manually or with a compatible scan tool


a compatible scan tool is also required to check the fuel tank pressure sensor.


This type of diagnostic with smoke machine and compatible scan tool runs 100 dollars at a shop.


I can tell you the Evap canister vent valve is by far the most common failure that cause p0446


so if I had to make my best guess without using the diagnostic equipment I would suspect the canister vent valve


click here to view location of the canister vent valve


click here for further information on testing for p0446


special tools are needed to diagnose it properly (smoke machine/compatible scan tool)


but as I mentioned I would suspect the Canister Vent Valve


let me know if you need more help