Outstanding idea, Danimal.

I've been very faithful to run only 93 octane in the car since I bought it, but I'm fairly certain from time to time I've also used ethanol 'enhanced' fuels. I have no idea if that would cause the sensors to report something, but it's definitely worth a try.

I did notice that the warning comes on during certain temperatures, so there might be a link there, too.

Thanks again!