E18
Stiebel Eltron External Sensor / Remote Control Fault

Display shows E18 and unit does not heat; often appears on models with external temperature sensors or remote controls.

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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

Disconnected or damaged external temperature sensor, Faulty remote control module, Incorrect configuration for external control, Broken low-voltage wiring to external device

How to Fix / Troubleshooting

Safety: Turn off power before working on low-voltage connections.

  • Check configuration: Verify in the installer menu (if available) whether an external sensor or remote is enabled. Disable it if not used.
  • Inspect external wiring: Follow the low-voltage wires from the heater to any external sensor or remote. Look for breaks, loose terminals, or damage.
  • Bypass test: Temporarily disconnect the external sensor/remote and configure the unit for internal control only. Restore power and see if E18 clears.
  • Replace faulty device: If the error only occurs when the external device is connected, replace the external sensor or remote control module with the correct OEM part.
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Repair Difficulty

Medium 3/5

Required Part

External Temperature Sensor / Remote Control Module
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