I ran IID tool yesterday and saw a couple of strange ground faults. One re: an antenna and another (multiple instances) re: the e-brake, which I largely stopped using years ago. I replaced the battery with a new H8 AGM. I got a check engine light and ran the tool again and now it was showing a more significant ground fault. I cleared all faults and drove the car for an errand about 15 miles. No issues and no faults so far. I get the feeling this was a battery problem. We'll see after another 100 miles or so.