Q: I have an evap system issue with a check engine light code P0456 for a "really small leak"

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I need help diagnosing a P0456 evap system code for a "really small leak" so far, I have changed the purge valve and gas cap and neither of those worked because the light came back on. I took it to get smoke tested but they found no leaks. So now I don't know what to do thanks! If it helps, I do sometimes notice that my RPMs are pretty high on the freeway, at around 4K going 75-80 miles an hour which seems quite excessive to me, but I don't remember if that's how inefficient my car has always been before this issue.

My car has 128500 miles.
My car has an automatic transmission.

Hi there. Unless you have professional EVAP system leak detection equipment, there really isn’t much more you can do to isolate or diagnose the source of your EVAP leak or warning light. The one thing we can suggest is to read this article on the P0456 OBD-II trouble code to review all possible sources and repair suggestions.

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