A few years ago, I bought a used car. The dealer assured me it had just been fully serviced, but I noticed a warning flag on the dashboard, it said “Maintenance Required.” Every car requires regular maintenance, but I figured this was a warning about something specific. It seemed to drive OK, it didn’t seem to have anything wrong.
After a few thousand miles, I took it in for an oil change, but the light stayed on. Eventually I had to do some major repairs. The clutch cylinder had to be replaced. The light stayed on. I had to replace the timing chain and the steering rack, that was a really expensive repair. But still the light stayed on.
After replacing the steering rack, I had to take the car to another shop to have the wheels aligned. There really was nothing left on the car that hadn’t been serviced, but that damn Maintenance Required flag was still on. I mentioned this to the mechanic, he seemed puzzled and said, “lemme see that.” So he got in the car and looked, then he took the key and poked it into a little slot under the flag, and it reset. The flag was gone.
I asked him what happened. He said the flag is hooked to the odometer, it goes off every 5000 miles to tell you to change the oil. But the car doesn’t know when you changed the oil, the mechanic has to reset the flag manually.