Circuit Description

While engine is warming, PCM reads Engine Coolant Temperature (ECT) sensor to determine how long it takes coolant to reach temperature required for closed loop operation. PCM compares actual time required to a predetermined time. DTC will set if closed loop operation temperature of 68°F (20°C) is not reached within 2-5 minutes of engine start-up.

For duplication of DTC, ensure no ECT or IAT DTCs are set, IAT is greater than 19°F (-7°C), and ECT is greater than -40°F (-40°C).