2002 Dodge Caravan Maintenance Diagnostic light

About a month ago the maintenance diagnostic light came on. The manual says it's due to bad gas, loose fuel cap or leak in emission system (if the light on the panel is steady not flashing) I ruled out bad gas and loose gas cap. I checked all the air lines/hoses and did find one line disconnected in the back of the engine that leads to the air filter and also found what appeared to be an unused vacuum line that wasn't covered. I put the line back on and capped off the unused vacuum line. The light went off right away. However, about a week ago it came back on. Then I ran a diagnostic which said minor leak in emission system. I looked at every single area but there are no visible issues. I was told in some cases the light on the panel comes on but it's no big issue and won't affect performance or mileage but I'm not sure. Thoughts? Thanks.