10.4 sir i was thinking on that. ill surely buy it and thanks a lot for the replyThe valve is in back above the spare tire and its part of you emissions test that the computer periodically does. Probably wont hurt not fixing right away but is something that should be addressed in the near future. I have heard that if the computer senses something wrong with emissions it can mess up other components like o2 sensors. May also cause the truck to run rich and thats not good on the cat either.