Takagi Bypass Valve Failure (if equipped)

Takagi controller shows error 661; unit may not modulate correctly or may not fire.

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.

Possible Causes

Stuck bypass valve, Failed bypass valve motor, Scale buildup in bypass passage, Wiring or PCB control fault

Safety first: Turn OFF power, gas, and water. Relieve pressure before opening water components.

Steps:

1. Descale system: Perform a full descaling flush to remove mineral buildup that can jam the bypass valve.
2. Inspect wiring: Locate the bypass valve motor and check its wiring harness and connector. Reseat connectors.
3. Reset and test: Restore power and gas, clear the error, and test operation.
4. Professional service: If error 661 remains, the bypass valve assembly or control board may need replacement by a qualified technician.

Hard 4/5

Bypass Valve Assembly

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