Question about GMC Envoy
This is refered to the DTC EVAP Large Leak Detected - The ECM has detected a large leak in the EVAP system during a system monitor test
1. Defective, loose or missing fuel cap
2. EVAP canister broke, hose cracked or not connected
3. Purge or vent solenoid defective
4. Vacuum leak at engine
So, since you replaced the gas cap already, it sounds like checking the EVAP canister and related hoses would be the next thing to do. If there are no obvious loose or broken hoses or anything, you may have to acquire more info from a Chilton's Total Car Care or Haynes manual, or some professional-grade manual, in order to check the operation of the solenoids. Check with your local Library. Mine has online access to AllData and Mitchells, besides paper versions of Chilton's TCC you can check out. Take a thumb-drive with you, and you can save whole web pages or diagrams as needed.
A smoke machine is nice, especially if you're lazy, but hardly necessary to fix these problems most of the time. If you know where all the hoses are to check them, and how to check the solenoids, there really isn't much else left.
I hope helps (remember to rate this asnwer).
Posted on Oct 07, 2010
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Posted on Jan 02, 2017
SOURCE: check engine light on
The codes you are getting can be caused by one of the several parts to the canister purge valve. It would best be taken to a mechanic or you may be replacing parts that you don't need. Normally the evap canister purge valve has stuck or broken or disconnected.
Posted on Jan 26, 2010
Change the evap vent solenoid canister located near the master cylinder on the right side of the engine or your hoses may be cracked. Good luck!
Posted on Mar 12, 2009
you should be able to fix it look for a can near the fuel tank that has vacuum hoses coming out of it and you should be able to just buy the bad solenoid
Posted on Nov 03, 2008
SOURCE: What do we do when
P0446 could be a bad purge valve, bad ecm, or wiring between. the only way to know is to have a mechanic diagnose it. It needs to be repaired if you want the engine light off. If you let it go, the ecm cannot tell you if other problems are happening because the light is already/still on.
Posted on Sep 10, 2010
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