Dear Car Talk:

I have a 1996 Honda Accord with 161,000 miles. I am the second owner, but I've had it since '97, and it is the most mechanically reliable car I have ever owned. In the past few months, it has developed an intermittent issue. Sometimes -- not always, but more than half the time -- when I start on a drive, the air bag warning light comes on. If the trip is short, the light (if it came on) will stay on the entire time.

But if the trip is longer, after 30 minutes or so the light goes off. If the light never came on, or if it goes out during a trip, once it is out, it doesn't come back on during that trip. Is this something I should worry about? -- Albert



Not unless you think you might need the air bag someday, Albert.

Air bags have a "self-diagnostic" system that takes a few seconds to run every time you start your car. So each time you start up your Accord, the computer checks to make sure all the components necessary to deploy your air bags are present, accounted for and working.

While the car is testing the air bag circuits, you'll see the air bag (or SRS) light on your dashboard. Once the system has checked out and is ready to go, the light will go off. So if the light is on, at least one of your air bags won't function if you need it.

On a 20-year-old car, it could be almost any part of the system. It could be a faulty sensor, a bad air bag module, a bad clock spring or a problem with a wiring harness somewhere. And you're going to need a mechanic to scan the car for you and track it down.

In the meantime, keep your Bronko Nagurski football helmet on the passenger seat. And if the air bag light doesn't go off after a few seconds, fasten that chin strap.

And needless to say, you'll want to get it fixed as soon as you can, Albert.