DTC P0115: ECT Sensor Circuit: Description
An Engine Coolant Temperature (ECT) sensor monitors the temperature of the coolant. This input is used by the Engine Control Module (ECM) for engine control and as an enabling criteria for some diagnostics.
The airflow into the engine is accumulated and used to determine if the vehicle has been driven within the conditions that would allow the engine coolant to heat up normally. If the coolant temperature does not increase normally, the diagnostics that use engine coolant temperature as enabling criteria may not run when expected.
This DTC will only run once per ignition cycle within the enabling conditions.
If the ECM detects the calibrated amount of airflow and engine run time have been met, and the engine coolant has not met the calibrated temperature, DTC P0115 sets.