E2
Lux Room Temperature Sensor Short Circuit

Thermostat displays E2 and shows incorrect or no temperature reading

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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

Shorted internal thermistor on main PCB, Conductive debris bridging sensor leads, Moisture ingress on sensor area

How to Fix / Troubleshooting

Safety: Turn off HVAC power at the breaker before handling the thermostat.

  • Remove thermostat: Pull the Lux thermostat off the wall plate carefully.
  • Check for moisture: Inspect the vent openings and sensor area for condensation, water stains, or corrosion. If moisture is present, allow the thermostat to dry in a warm, dry room for several hours (do not use direct heat).
  • Clean debris: Use compressed air or a soft brush to remove dust or metallic debris that could short the sensor leads.
  • Reinstall and reset: Reattach the thermostat to the wall plate, restore power, and perform a factory reset from the settings menu.
  • Verify temperature: Compare the displayed temperature to a known-good thermometer. If E2 persists or readings are wildly inaccurate, the internal sensor is shorted and the thermostat must be replaced.

If the unit is under warranty, contact Lux support with the model and serial number before replacing.

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Repair Difficulty

Hard 4/5

Required Part

Lux Smart Thermostat Main PCB (integrated thermistor)
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