So, we have a 2013 Accord ex-l 4cyl sedan. Last night my daughter unlocks her door using the fob, few minutes laters comes back in, "Car won't start". I go to check it out, door locks not working with the fob, trunk won't open with the fob, car doesn't start up ( no dash lights of any kind ), headlights won't even turn on, getting zero power. I tested the battery, 12.6V on the nose. Next thing, simply disco'd the neg batt cable and let it sit for a few minutes, reconnected it and everything is back to "normal". I started up the car and tested the battery again to make sure it was charging properly and it was, solid 14.4V under load. Not sure what to make of it. The battery cables were firmly attached to the terminals before I disconnected the negative. Any ideas on what or where to look?

 

You may need to replace the negative cable battery sensor at the negative post on your battery.

 

I thought about doing that. After some later troubleshooting, I found that the ground wire ( attached to the sensor ) had some slight play to it; the bolt securing the ground wire to the sensor was loose, and the wire was able to shift around a bit. Tightened it down, 10 days, no issues. Maybe that was the issue?