102 NPE Service Manual
Check method
Fault Possible Causes Check method
Defective sensor
Defective temperature
sensor connector
Check if the cold water temperature sensor is open and if the connector is attached
properly.
Temperature sensor
●
Measure the temperature sensor resistance. (Defective if it is 30k or higher.)
●
Replace the temperature sensor if the resistance is abnormal
Other trouble
Defective PCB If the issue continues despite the checking the items above replace the PCB.
Direct water temperature sensor Check if the water temperature sensor is open.
Error type: M Open
5.1.14 434Error
Error occurrence conditions and check items
Error Description
E434
Water Adjustment valve
error
If the water adjustment valve does not work properly due to a defective feedback sensor, water adjustment
valve, or PCB board, the system displays 434E (cleared automatically/manually).<only when in CASCADE mode>
●
Water adjustment valve error – The system commands opening of the water adjustment valve, but the valve
remains closed. [Check the feedback sensor.] (Cleared manually)
●
If the Water adjustment valve sensor open/short-circuit is detected, the system displays an error message. If
flow is sensed, the system clears the error automatically and provides the hot water. If open/short-circuit is
detected after hot water is used, the system displays the error message.
Check items
If the 434 error occurs, connect the Water adjustment valve to the PCB. The valve must be kept open when the
water heater is not operating. If the PCB is defective, the motor keeps operating and the valve continues to make
attempts to open/close.
1. Defective water adjustment valve
2. Defective PCB
3. Check the operation of the water adjustment valve using the Component Test mode (refer to page 47).
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