Malfunction Indicator Light (MIL)

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.

PCM illuminates the MIL (service engine soon or check engine) when the following occurs:

PCM detects a malfunction in the emissions system.
PCM performs displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.
Ignition switch is in RUN position, with engine off.