p0496 code please help

Hi I have a 2004 silverado crew cab with the 5.3 and 88000 miles or so, the other morning it threw two of the same code a p0496. My scanner read a evap high purge flow fault. I tried searching on here and couldn't find anything on that code. Has anyone else had this problem or know how to fix it? The truck runs fine, idles fine it just keeps throwing this code. Any help would be great. Thanks Jay

Code is for undesired intake vacuum flow to EVAP system.
Any other codes?
Code can be caused by bad coolant sensor or shorted VCM purge solenoid or tank pressure sensor or even bad wiring.

To test for code get a good engine capable scanner and wiring diagram and a good volt/ohm meter and a real good repair manual and go threw the repair flow chart for that code.
http://www.alldata.com/products/diy/index.html

Let us know how it goes.

Thanks a lot I will work on it tomorrow and let everyone know what I come up with. Could it be the gas that I ran in this tank? The gas pump said it contained 10% ethonal, but I drove it about 120 miles on the tank before it threw the code.

You are welcome.
No on the gas.
Let us know what the test for code 496 shows.
Good Luck

this might also help
http://www.automotiveforums.com/t919886-_04_av_p0496_code.html

Hi I have a 2004 silverado crew cab with the 5.3 and 88000 miles or so, the other morning it threw two of the same code a p0496. My scanner read a evap high purge flow fault. I tried searching on here and couldn't find anything on that code. Has anyone else had this problem or know how to fix it? The truck runs fine, idles fine it just keeps throwing this code. Any help would be great. Thanks Jay

when refueling the engine should be off,insure the cap is correct and good. the cannister lines must be checked..

I believe this will throw when the fuel tank has too much of a vacuum....this could be a stuck valve or a bad cannister...

when you open the fuel cap does is sound like a lot of vacuum ? the cap is designed to allow air to enter the fuel tank when the vacuum is at a certain level...if its wrong this could be it..

also running the fuel tank very low does this dtc as well...

you can also check the cannister lines for black residue..if found this usually means that the cannister has had fuel saturation..

Well I took the little filter by the canister and cleaned it, and pulled all the lines and wires off on and around the canister. everything looked normal except for the dust in the little filter. Put it all back tobether and dumped a bottle of lucas fuel treatment and so far so good no codes. Thanks again for all of the help this site is a life saver.