We took Diane’s Prius to the mechanic today so they could work on it tomorrow; the “Check Engine” light and the red triangle of death stayed off on the drive.

The mechanic scanned the car and got a U0111 code, which means that the computer lost contact with the energy management system (or something like that).

His best guess is that the 12-volt battery is weak and having the car idling for a while during the smog test triggered the error, but they’ll do more research tomorrow to make sure it’s worth changing the oil. It better be – we have nearly a full tank of gas in the car!

I had to take Diane’s 2005 Prius for a smog check before we could renew its registration. The mechanic did the test, told me the car passed and gave me the certificate – then he asked me if I knew that the car said it needed maintenance. I did – the light had come on a few days ago and I planned to get it done this week.

After that, he asked me if I knew the “Check Engine” light was on – that was news to me! He said it came on right after the test results were logged, so he didn’t have to fail the car but suggested I get it looked at.

I drove home (the car seemed fine) and called my regular mechanic at Auto-Tec to make an appointment. An unfamiliar voice answered the phone; the previous owner had sold the business! But the same mechanics are there, and recent Yelp reviews are still positive, so I made an appointment for Friday.

I wanted to take a photo of the problem for the blog, but when I started the car a couple of hours later, the warning light was gone. I hope that’s a good sign, but I’m going to wait to send in the registration until I know more.