Oil Life Reset
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The IPC illuminates the OIL LIFE RESET message when the PCM determines that the engine oil should be changed. The IPC receives a class 2 message from the PCM indicating the remaining oil life percent. Once the oil is changed, perform the engine oil monitor reset procedure in order to clear the Change Engine Oil indicator. Refer to GM Oil Life System - Resetting in Maintenance and Lubrication.