This "SERVICE" light is located in the instrument panel and informs the drive that a problem has occurred that requires the vehicle to be taken in for service as soon as possible.
This light is used for non-emission related failures. Malfunction often will be indicated by the system before any problem is apparent, which may prevent more serious damage to your Saturn. This system is also designed to assist your service technician in correctly diagnosing any malfunction.
As a bulb check, the light will come on with the ignition key on and then go out in 2 to 3 seconds. The light should go out when the engine is started. If the light remains on, the self-diagnostics system has detected a fault. If the problem corrects itself or goes away, the light will turn off 3 seconds after the self-diagnostic test is completed.