F41 displayed, furnace stops with pump/fan synchronization error

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

Defective Protherm pump speed control, Incorrect wiring between PCB and pump, PCB control output failure, Software configuration error

Safety first: Turn off power.

Step 1 – Inspect pump wiring: Check the connector from the PCB to the pump for secure fit and damage.
Step 2 – Reset control: Power cycle the furnace to clear temporary software errors.
Step 3 – Technician diagnostics: A technician should verify pump speed control signals and replace the pump or PCB if necessary.

Hard 4/5

Variable‑Speed Circulation Pump

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