218Error - Navien NHB-055 Service Manual

5.2.13 218Error

Error conditions and Check Items
Error
E218
Heat exchanger input temperature
sensor open
Check items
Version 1.0
If an error (open: MΩ) in the heat exchanger input temperature sensor is detected, the system
displays the 218E error 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 defected heat exchanger input temperature sensor.
3. Replace the controller.
Is the inlet thermistor
normal?
Yes
Check connector
(#3 and #4 of CN 13)
Description
No
Replace inlet thermistor
Resistance between #3 and #4 of CN13
is from 0.437kΩ to 176kΩ at normal
condition. (see page 63-64 for Wiring
Diagram)
Before measuring resistance of the
thermistor, detach the connector
from the PCB.
NHB Service Manual 109