Check engine light and read the pO430 code in daughter's jeep. Pretty sure we had this in the past and changed out an O2 sensor but don't remember which or how many. No missing, not sluggish, no issues driving whatsoever. Question is can I send her back to Austin without doing anything about it. Is it a big deal mechanically if everything seems normal.

If it's just the sensor again, it may be OK. I had a 2011 Jeep Grand Cherokee that would throw that code and I changed the sensors a couple of times. The CEL would eventually come back after a few months though, and we finally tied it back to a bad Catalytic converter. Put a new Cat on it, and I never had the problem again.