DTC P0128: Engine Coolant Temperature Excessive Time To Reach Operating Temperature: Description

While engine is warming, Powertrain Control Module (PCM) monitors Engine Coolant Temperature (ECT) sensor to determine the amount of time it takes engine to reach coolant temperature required for closed-loop operation. Airflow coming into engine is accumulated and used to determine if engine has been driven within conditions for engine coolant to heat up normally to thermostat regulating temperature. If coolant does not increase normally or does not reach regulating temperature, diagnostics may not run.