(F)65 Main Flow Control Valve Abnormality; (F)66 Bypass Flow Control Valve Abnormally; (F)70 Circuit Board Abnormality; (F)71 Gas Solenoid Valve Drive Circuit Abnormality - Noritz WHiC56 Service Manual

Error Code 65 Main flow control valve abnormally
Same matter from error message 65, page 6.
Error Code 66 Bypass flow control valve abnormally
Same matter from error message 66, page 7.
Error Code 70 Circuit Board abnormality
Disconnect the electrical power, then reconnect electrical power to the Unit to reset the system.
If the Circuit Board abnormality is continuous, replace the Circuit Board set.
Error Code 71 Gas Solenoid Valve drive circuit abnormality
Circuit Board abnormality
This error code is displayed due to failure on the circuit board (Gas Solenoid Valve drive circuit) or in the Gas Solenoid
Valve drive system's groundor or at High Limit Swich. The cause could be a welding issue on the Circuit Board or failure
of High Limit Swich . If High Limit Swich is normal the Circuit Board set should be replaced.
Error Code 72 Flame Rod circuit abnormality
(Detection of flame when no flame is present)
Disconnect the connector from the Flame Rod and to prevent grounding
the connector. And check whether "72" is displayed or not .
Not displayed Displayed
Error Code 73 Circuit board setting abnormality
Error Code F76 Multi-system communication error
• Check for the appliance that is not set, the gas type, model type, etc.
• Check whether the DIP switch settings has been changed while the water heater has a power.
• Check for proper connection of Quick Connect Cord.
<Condition of occurrence for error code 72>
This is displayed if the Flame Rod detects
a flame before ignition.
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Replace the Circuit Board set.
Replace the Flame Rod.