Service Engine Soon
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2001 GMC Savana Special, 2001 GMC Savana Camper Special, 2001 GMC Savana, 2001 Chevrolet RV Cutaway, and 2001 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
SERVICE ENGINE SOON warning indicator is part of computerized engine control system, and will illuminate when a malfunction or Diagnostic Trouble Code (DTC) exists. As a bulb check, indicator will illuminate when ignition is turned on. If no problem exists, indicator will go out when engine is started. Indicator will flash if a misfire condition is detected, or will stay on steady if an emission control system malfunction is detected.