F5
Poolex
Water Outlet Temperature Sensor Fault
Poolex pool heater displays F5 and stops heating; fan and compressor may not start.
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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 outlet NTC sensor, Loose or oxidized sensor connector, Broken sensor cable near Poolex titanium heat exchanger outlet, Fault on main control board sensor input
How to Fix / Troubleshooting
Safety: Disconnect power before accessing internal components.
What to check:
- Visual inspection: Locate the outlet temperature sensor on the water outlet side of the Poolex titanium heat exchanger. Inspect for physical damage or signs of overheating.
- Check cable routing: Ensure the cable is not pinched by the cabinet or rubbing against sharp metal edges.
- Reseat connectors: Unplug and replug the sensor connector at both ends (sensor and main PCB) to remove oxidation.
Sensor replacement:
- Purchase the correct Poolex water outlet NTC sensor for your model.
- Shut off water valves if the sensor is wet-side; relieve pressure.
- Remove the old sensor, install the new one with proper sealing, and reconnect wiring.
- Restore power and confirm that the F5 code is gone and outlet temperature readings are stable.
If F5 persists with a new sensor, the main control board may have a defective sensor input and should be evaluated by a professional.
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Repair Difficulty
Medium
3/5
Required Part
Water Outlet Temperature Sensor (NTC)
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