Service Engine/Throttle Soon Light

As a bulb and system check, SERVICE ENGINE/THROTTLE SOON light glows when ignition switch is turned to ON position and engine is not running. When engine is started, light should go out. If light does not operate as described, malfunction has been detected in computerized engine control system or SERVICE THROTTLE SOON light circuit is faulty.

To verify proper operation of SERVICE ENGINE SOON light on gasoline models, proceed to the DIAGNOSTIC CIRCUIT CHECK in BASIC TESTING - 4.3L article.