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.

Conditions required to set DTC are:

Warm Case Test

• No MAP, IAT, ECT, TP, Misfire, Injector or VSS DTCs set.
• Start-up ECT less than 84°F (29°C).
• Start-up IAT greater than 50°F (10°C).
• Accumulated airflow is greater than 1500 grams.
• Engine run time is more than 90 seconds.
• Time for coolant to reach stabilized closed loop value is less than 120 seconds.

Cold Case Test

• IAT is between 20°F (-7°C) and 50°F (10°C).
• Accumulated airflow is greater than 2000 grams.
• Engine run time is less than 225 seconds.
• Time for coolant to reach stabilized closed loop value is less than 300 seconds.

Other Case Test

• IAT is between -22°F (-30°C) and 20°F (-7°C).
• Accumulated airflow is greater than 3600 grams.
• Engine run time is less than 450 seconds.
• Time for coolant to reach stabilized closed loop value is less than 600 seconds.