F11
Protherm
Water Pressure Sensor Range / Signal Error
F11 displayed, furnace runs briefly then shuts down, may show high pressure
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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
Defective water pressure sensor, Short circuit in sensor wiring harness, Incorrect sensor type fitted to Protherm hydraulic block, Faulty analog input on PCB
How to Fix / Troubleshooting
Safety first: Turn off power. Allow system to cool.
- Step 1 – Compare gauge and display: If the mechanical gauge shows normal pressure but the display shows very high or very low values, suspect the sensor or wiring.
- Step 2 – Inspect wiring: Trace the cable from the pressure sensor to the PCB. Look for damage, kinks, or signs of overheating. Reseat the connector.
- Step 3 – Sensor replacement: If wiring is intact, replace the water pressure sensor with the correct Protherm part number. Be prepared for some water loss; isolate and drain as needed.
- Step 4 – PCB check: If a new sensor does not resolve F11, the PCB input may be defective. A technician should confirm and replace the board if necessary.
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Repair Difficulty
Medium
3/5
Required Part
Water Pressure Sensor
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