"It's ON"!
Your "check eng." light was not intended to alert you to possible devastating consequences, such as loss of engine oil pressure, overheating, etc.
It's purpose is to ensure that the engine's operation remains within the specifications established for it's exhaust emissions. However, continuing to drive the vehicle for a long period with the light "on" could prove damaging, in the event that one of the Engine Control Sensors critical to fuel mixture, or ignition spark advance, for example, is grossly screwing up.
Your PCM (computer) has detected an out-of-range-reading, or no reading, from one or more of it's input sensors, and has illuminated the MIL (Malfunction Indicator Light) to alert you to that fact, while storing a "code" which relates to that sensor(s) identity.
Failure of most of the sensors will NOT cause the engine to stop running, or sometimes even falter at all. A few, such as the Crankshaft Position Sensor, will cause a "dead in the water" condition upon failure. So, if the vehicle seems to be running normally, and makes no unusual sounds or vibrations, it is likely safe to drive it to a facility which can "read" the trouble code(s) that have been stored. imp
