Error - Navien NCB-700-2S+/42K Service Manual

5.2.14 Error 218

Error conditions and checklist
Error
E218
Open heat exchanger input temperature
sensor
Checklist
90 Troubleshooting
If an open (-10°C or lower) heat exchanger input temperature sensor is detected, the
system displays 218E on the front panel. If this occurs, the boiler initiates shutdown.
1. Check if the heat exchanger input temperature sensor connector is wet due to any
reason, including leakage.
2. Replace the defective heat exchanger input temperature sensor.
3. Replace the controller.
Is the inlet thermistor
normal?
Yes
Check connections
Description
No
Replace inlet thermistor
Before measuring thermistor
resistance, disconnect it from the
PCB.