Hello, I'm brand new to this forum but wanted to share my experience as I was unable to find any answers after searching this and many other forums on the Internet.

My 2007 Ram 1500 with the 5.7L Hemi gave me the "Gascap" message in the odometer. It had already been two weeks since I last filled up so I didn't think it was a loose gas cap but I tightened it anyway. When this didn't solve the problem, I checked all the hoses around the evap canister, filler neck, and under the hood but didn't find any cracks or loose clips.

Also, even though the manual says that after the system detects a leak twice in a row the Check Engine Light would come on, this did not happen even after at least 20 drive cycles. Finally I broke down at took my truck into the dealer.

The mechanic found that even though the "Gascap" message was being displayed, the computer was reporting that no faults were found in the system. They proceeded to re-flash the computer, and after doing so the computer immediately reported that the Evaporative System Integrity Module (ESIM) was faulty. It was a $15 part and after that everything was as good as new.

As a side benefit of the re-flashing, apparently the shift points and fuel mapping were changed, and just like they predicted I've gained approximately 1.5 - 2 mpg. I just wanted to put this out there for anybody who is getting the "Gascap" message in the odometer but finds that the computer is not storing any codes to indicate that it found a problem.

 

Good find... Probably 95% of the time it is an actual leak and a CEL pops up, but its good to know what to do when there is no CEL...

 

Unfortunately, there are good reasons to visit the stealership, like when the bolt vibrated free from my drivers side lower shock mount, due to a faulty autozone 130 hub.

Thankfully the stealership allowed me to purchase the new bolt at $58 us. Sometimes it is a must.