Howdy. A puzzler here- I have a 2013 TUndra Crew Max with the 4.6L. I have a Check Engine Light pop-up maybe once every two weeks. It usually comes on when I first start it up in the morning. It may stay on all day, it may stay on for 30 minutes. It is never consistent. I did have it checked at the car parts store and all they said was a P0440 code. But that could be a dozen different causes. How do I narrow it down? How come it is never consistent? Thanks!