F02 indicates the supply temperature sensor of the boiler has failed. The boiler will not restart until a technician replaces the sensor and pushes RESET on the display. This is a serious safety issue as indicated by the illuminated red light and the word LOCKOUT flashing on the display. During this lockout fault, the pump will be on.
- Check the electrical connection to the thermistor on the outlet manifold. Verify 5 VDC by checking the Molex connector. If there is no 5 VDC, check the harness. If harness is OK, replace the control. Verify thermistor values.
- Replace thermistor if necessary.
NOTE: The boiler will reset automatically once the fault is corrected.
