What do you think ESS is? It says service ESS because something is wrong with your Jeep and it is 100% guaranteed to be an issue at some point. You should get it fixed.Iām glad the auxiliary battery not being charged without ESS is false. Iāve been delighted to see the last few weeks āservice ESSā when starting. I donāt have to remember to hit the button. I plan to never have it fixed unless it causes another problem.