Warm-up Cycle

The ECM 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 40°F (22°C) from the start-up temperature. The engine coolant must also achieve a minimum temperature of 160°F (71°C). The ECM counts the number of warm-up cycles to clear the Malfunction Indicator Light (MIL). The ECM will clear the DTCs when 40 consecutive warm-up cycles occur without a malfunction.