Following along because I'm in the same boat. The three lights are up. Tightened the old cap and lights went away for a week. Came back, bought a new gas cap, and now effect yet. Any advice on a code reader based on your research?Update
Finally got a Code Reader and the code it pulled up was
Evaporative System ( very small leak)
Sounds like the ole gas cap
I have a brand new OEM cap but I know from experience with my old Rubicon that don’t mean a lot. I fought that battle for ten years on my Jeep and finally doubled up the gasket and good bye warning light. Going to cap gasket check and report back
Cheers Baja Charlie