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

Engine Coolant Temperature (ECT) sensor monitors coolant temperature. This input is used by Powertrain Control Module (PCM) for engine control and as an enabling criteria for some diagnostics. Airflow coming into engine is accumulated and used to determine if engine has been driven within conditions that would allow engine coolant to heat up normally to thermostat regulating temperature. If coolant temperature does not increase normally or does not reach regulating temperature of thermostat, diagnostics that use engine coolant temperature as enabling criteria, may not run when expected. If engine coolant fails to reach a preset target temperature before a calculated airflow is accumulated DTC P0128 will set. This DTC will only run once per ignition cycle within enabling condition.