Coolant temperature sensor
Coolant-temperature codes describe the sensor circuit, not only a hot engine.
P0117 is a low input and P0115 is a circuit fault. P0128 is the warm-up monitor and often points at the thermostat rather than the sensor.
A wrong temperature signal changes fueling and fan control. Confirm which code is stored, then follow that DTC page.
A trouble code marks a condition to test. It does not by itself prove which part to replace.