Change Engine Oil
WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
The IPC illuminates the CHANGE ENGINE OIL indicator when a class 2 message from the body control module (BCM) requests illumination. The BCM receives a CAN serial data message from the engine control module (ECM) when the ECM determines that the engine oil should be changed. After the oil is changed, reset the engine oil monitor. Refer to GM Oil Life System - Resetting in Maintenance and Lubrication.