Re: Check Engine - Code P0456
Hi. A little late to the party but I have the solution. This is not a Evap leak as you are all saying. I have 2005 Jeep Grand Cherokee limited with the 5.7l hemi and just had the same issue. Saying check gas cap but the engine was running fine. I went to Autozone and ordered the Leak detection pump or vapor detection pump as it's called both for 50.00s and replaced the old one and it fixed the issue. The problem is the pressure is controlled by a sensor in that pump that when it goes bad it tells you that you have a bad leak as it can't read the full pressure. It also detects the vapors in the system. Hope that helps.