Warm-Up Cycles
WARNING: This page is about a different car, the 2003 Buick Regal, 2003 Buick Century, 2002 Buick Regal, and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
The PCM uses warm-up cycles to run some diagnostics and to clear any Diagnostic Trouble Codes (DTCs). A warm-up cycle occurs when the engine coolant temperature increases 72°F (22°C) from the start-up temperature. The engine coolant must also achieve a minimum temperature of 160°F (71°C). The PCM counts the number of warm-up cycles in order to clear the Malfunction Indicator Light (MIL). The PCM will clear the DTCs when 40 consecutive warm-up cycles occur without a malfunction.