651
Takagi
Flow Adjustment Valve Failure (if equipped)
Error 651 displayed; unit will not operate.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Stuck flow adjustment valve, Failed flow control motor, Damaged wiring to flow adjustment valve, Faulty PCB control circuit
How to Fix / Troubleshooting
Safety first: Turn OFF power, gas, and water supply. Relieve water pressure before removing any water-side components.
Steps:
- 1. Check water quality: Heavy scale or debris can cause the flow adjustment valve to stick. If your area has hard water, plan for descaling and filtration.
- 2. Inspect wiring: Locate the flow adjustment valve assembly and check its wiring harness for damage or loose connectors. Reseat connectors.
- 3. Descale system: Perform a full heat exchanger and internal water path descaling using a flush kit and descaling solution. This can sometimes free a sticking valve.
- 4. Professional replacement: If error 651 persists, the flow adjustment valve or its motor may need replacement, which is best done by a technician due to internal sealing and calibration requirements.
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Repair Difficulty
Hard
4/5
Required Part
Flow Adjustment Valve
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