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 time for engine coolant temperature to reach 70°F (21°C) exceeds a predetermined amount of time.

For duplication of DTC, ensure no IAT or ECT sensor DTCs are present, minimum air temperature is greater than 19°F (-7°C), coolant temperature is greater than -40°F (-40°C), and start-up engine coolant temperature is less than 122°F (50°C).