Your heat pump has stopped working because a sensor that monitors the temperature of the outgoing refrigerant gas is reporting an incorrect or faulty reading.

Discharge Thermistor (Tp) Error

What causes this fault?

This fault occurs when the system's control board receives an impossible or unstable temperature reading from the sensor on the compressor outlet. The most common reason is a physical failure of the internal sensor components or a loose wiring connection that prevents the heat pump from safely monitoring its own operating temperature.