E08
Pentair
Outlet Water Temperature Sensor Fault
Heater displays E08 and 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
Failed outlet temperature sensor (thermistor), Loose or corroded sensor connector, Damaged sensor wiring harness, Control board input fault
How to Fix / Troubleshooting
Safety: Turn off power to the heater before accessing internal components.
- Locate outlet sensor: The outlet water temperature sensor is typically threaded into the outlet side of the header/manifold.
- Inspect wiring: Check the sensor harness for cuts, rodent damage, or pulled connectors. Reseat the plug on both the sensor and control board.
- Test sensor: Disconnect the sensor and measure resistance with a multimeter. Compare to Pentair’s thermistor chart for the current water temperature. If readings are open, shorted, or far off spec, replace the sensor.
- Control board check: If a known-good sensor still results in E08, the main control board may have a failed sensor input and should be evaluated by a technician.
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Repair Difficulty
Medium
3/5
Required Part
Outlet Water Temperature Sensor
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