Gas Cap Check Engine Light

[Phillyrube]

Got an intermittent Check Engine light for vacuum leak in emissions system. Translate to gas cap. Replaced the cap, reset, and no light....for a few miles. Got 150 miles once before it kicked on. Reset, light out....Repeat.
Checked as much of the vacuum lines around the fuel tank and forward as I can but no obvious leaks or wear.
Any ideas?

 

[3pedals]

I’ve had the same issue in my truck for over 300k miles (currently at 425k). There is a large Evap leak somewhere that I haven’t been able to track down (nor have I really tried very hard) and new gas cap never solved the issue. It has been suggested to me that the problem lies in the fuel filler neck, but the only way to know the cause for sure is a smoke test.

 

[jws123]

You will have to use a smoke machine to find the leak also I have bad bad luck and good luck with aftermarket caps depends where they come from lol. So basically i just stick to the over priced oem caps now less issues thus far.

 

[Bills86e]

just below is the evap module, just press the tab to pull it off the slider clip holder, then push the red small end in on the electric connector to remove that.
replace is reverse.

 

[Jhon Matheew]

The EVAP or Evaporative Emission Control System prevents fuel vapors from being released into the environment. If there’s an issue with this system, it can trigger the Check Engine light. The EVAP system consists of several parts including the gas cap, vacuum feed line, gas tank filler tube, charcoal canister, and vacuum control valve. A leak in any of these parts can cause the Check Engine light to come on.