E11
Attack Return Temperature Sensor Fault (NTC Open/Short)

Boiler shows E11; may be related to return temperature sensor reading out of range.

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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 return NTC sensor on Attack boiler, Loose or corroded sensor connector, Damaged sensor cable, PCB input fault

How to Fix / Troubleshooting

Safety: Isolate power before working inside the boiler.

Steps:

  • Locate return NTC: Find the sensor on the return pipe entering the Attack heat exchanger or hydraulic block.
  • Inspect and clean: Check for moisture, corrosion, or physical damage. Clean the connector and reseat firmly.
  • Compare temperatures: If the display shows unrealistic return temperatures (e.g., -40°C or 130°C), the sensor is likely faulty.
  • Replace sensor: Unscrew or unclip the NTC and install a genuine Attack return NTC sensor, ensuring proper sealing.

Technician: If a new sensor does not clear E11, the PCB may require replacement by a professional.

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Repair Difficulty

Medium 3/5

Required Part

Return NTC Temperature Sensor
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