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2005 Jeep Grand Cherokee phantom emission leak?

My jeep shows a “check engine” light code regularly. I take it to my AAA garage and work with the manager. He checks the code and says it’s a "small’’ emission leak. Tried a new gas cap and not fixed. Tried to put “smoke” through the system and the leak could not be found. It seems mileage related, and about every month (approx. 250 miles) the light comes back on. I bring it to my AAA garage and the manager again checks the code and then turns off the light. He says it causes no problems and the leak can’t be found. He says just keep bringing it in and he’ll keep turning it off. He does not charge me for this service. Any idea what the problem is and how it can be located? Also, am I doing any damage to the engine?

So is this a P0456?? Small evap leak? It is annoying but won’t hurt the engine.

Buy your own code reader that allows you to reset the light yourself and save a trip. There are phone apps that can do this with a simple plug in “dongle” to the OBD2 port.

not sure of code, but yes it’s a small evap leak…

You need to find a better shop

An evap leak code doesn’t necessarily mean there’s a leak

It means the evap system could not build up and maintain a specified amount of vacuum

Did the guys at the shop even verify that the system could attain that vacuum . . . ?

Example . . . on some cars an evap leak code will be generated when a bad evap purge valve won’t pull a vacuum at all. In those cases you can smoke test all day long and everything will look okay, because the guy doing the testing doesn’t understand how the fault code is generated