P0115 - Engine Coolant Temperature Sensor 1 Circuit
Engine Coolant Temperature is monitored to allow the ECM to accurately adjust fueling and emission control systems, it will also normally be used to control cooling fan operation
Fault Code Explained
The ECM has detected an undefined fault with the Engine Coolant Temperature Sensor signal. The signal may be outside of it’s normal operating parameters, not responding to engine changes as expected or providing values that are inconsistent with the current operating conditions.
If possible use a diagnostic computer to view live data readings for the sensor and compare to actual coolant temperature. Test sensor supply Voltage and output signal