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Hello all,

The other morning I turned on the truck and the check engine light stayed on after all of the lights usually turn off. I immediately got out and checked the normal things, oil, tranny...things like that, tightened the gas cap, it still stayed on. So I drove to Autozone and had them read the OBDII code and it came up 42 (i think) which was a small evap leak. I felt the gas cap and it was secured but felt kind of loose, so I bought a gas cap and exchanged it out. Well it has been about 2 days now, and the light still has not gone off...What else could be causing the evap leak??

It is an 05' Silverado z71 with about 50,000 miles.

Thanks in advance!

AJ
 

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Did they clear the code after reading it? If the cap was the problem, the light will stay on for a while before going out. Have them clear it, and if it comes back on, then you know it wasn't the cap...

Start there, after that, they should have the OBDII manual, which tells you several different options. If not, I googled mine, and found all kinds of help...

Hope that helps.
 

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It's hard to keep all these trouble code procedures straight. If not already cleared, is this one that will self-clear after 50 starts, or will a brief power interruption clear the code?
 

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the 42 is listed as specific to the carbon canister and small leak, in the engine compartment but it will throw for the gas cap too, the gas cap is actually 41, get a new gas cap , then clear the codes and have no problems, i have been in the clear now for two weeks
 

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FYI: The California Air Resources Board (the infamous CARB) says carbon canister problems are prolific, so they have added a comprehensive Low Pressure Fuel Evaporative Test to the Smog Test inspection for 1976-95 pre-OBDII vehicles.
Perhaps, some day there be CARB approved jars to fart in.
 
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