One problem related to gas recirculation valve (egr valve) has been reported for the 2015 Jeep Wrangler. The most recently reported issues are listed below.
I own a 2015 Jeep Wrangler. In mid-2019 I noticed the heating system was not operating well. For example, when I turned the heat on, it would intermittently send warm and then cool air out of the blowers. One 38 degree day, it sent out no heat at all. In October 2019, the anti-freeze fluid level was low and it was filled. In Dec 2019, the entire reserve tank was empty. No fluid was visible in the radiator when the radiator cap was removed. I have observed when the car has been driven for 3-5 miles and then turned off, there is a slight odor of anti-freeze. It appears my vehicle may have a defective heater core.