Historically, the "check engine" light, which is usually an orange light overlaid with a symbolic representation of an engine, is also called an "idiot light". This is particular to some older car models, which have an unlabeled red light ("trouble" indicator). In particular, early 1980s Fords without the instrument option had only one light, which indicated low oil pressure, overheating and carburetion problems without distinguishing between them.
In modern electronic fuel-injected cars the "check engine" light usually only indicates minor problems that do not require immediate attention. It might, for instance, indicate that the fuel-injection computer has detected a reading from a failed sensor and has changed to open loop mode, meaning that the computer is no longer adjusting the engine's parameters according to conditions and exhaust. If this is the case, performance and gas mileage will suffer and the catalytic converter may be eventually damaged. Mechanics often refer to this state as "limp-home mode." A comprehensive instrument panel includes both gauges and alert lights: gauges to give a precise indication of coolant temperature, oil pressure, charging current, and voltage; and lights to catch the driver's attention when readings approach the "danger zone".
CLICK&CLACKTALKCARS: ; Pet seat belt barking up right tree; A little black tape will help solve 'idiot light' problem
Nov 20, 2000; DEAR Tom and Ray: I don't remember anyone writing to you with the problem of a dog or cat bouncing off the dashboard due to a...
Doesn't this sound like an idiot light? Uncle Al's next million-dollar idea has an auto motive.(SOURCE)(AL SICHERMAN)
Aug 21, 2006; Byline: Al Sicherman; Staff Writer A cluster of recent birthdays has caused Uncle Al to reflect on the many improvements in the...