I found out that before California will transfer the title to my nephew, I, as the "seller", have to provide a current CA smog certificate. In this part of AZ smog tests aren't required, so the car hasn't been tested in at least 10 years. If I drive the Civic over there and it won't pass the smog test, it puts me between a rock and a hard place, so I figured the safest thing would be to make sure the car will pass in Phoenix; if it won't pass there, it won't pass in CA.
The car has had an odd idling issue; when pulling up to a stop at a light, the RPM without any throttle first drops to 1300-1500 RPM, then drops to 400 RPM, then climbs up to a normal 600-650 RPM. It never stalls, but it feels like it's going to when the RPM drops that low and the engine shudders before it recovers. The check engine light never comes on.
I did a scan, and it showed a P1298 "electrical load detector circuit high voltage". WTF?? After much research, it turns out that Honda has a rather unique charging system, where the computer adjusts the charging voltage; a normal system, like on our bikes, tries to maintain 14.5V +/- all the time, the car system only outputs the higher voltage long enough to recharge the battery, then backs off to 13V or less. In theory, the lower voltage produces less drag on the engine, as well as not constantly overcharging the battery, especially on long duration drives without a lot of start cycles. A faulty ELD is a possible cause for the idle issue, and itself is suspect; there is a field service bulletin that mentions a bad solder joint.
I'll pick up a new one tomorrow from O'Reilly's.