Key fob battery died.
battery is good as I can lock/unlock/remote start using keyKey fob battery died.
I think there is a key sensor in the trunk area also. At least in the Clarity, don't know about the Civic. In fact I think I remember someone saying there are three sensors in total. But still could be a weak fob battery, that would certainly be the easiest thing to try first.Replace the battery. The distance that the keyfob will transmit falls off as the battery depletes. The distance to the door and start button are a lot closer than the trunk to the start button.
I finally bit the bullet, and bought the battery tester recommended here (by 2002?). It tests a couple dozen battery types under load. Works like a champ, to identify weak batteries. Pricey, though.A few days ago my son complained that the door did not unlock when touched on occasion. I popped out the battery and measured the voltage with a multimeter compared to a new one.
Old: 3.0x V
New: 3.3x V
I asked if the car warned of a low battery, and he said he didn't think so. I replaced it and so far so good. (I did notice last time I replaced a low battery with warning it was in the 3.0x V range so I told him it's about time to change it anyways)...