E16
Potterton DHW Flow Sensor / Turbine Fault

Boiler intermittently locks out with E16, particularly during hot water use

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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

Sticking DHW flow turbine, Blocked inlet filter, Faulty flow sensor, Limescale in DHW inlet

How to Fix / Troubleshooting

Safety first: Turn off power and close the cold water isolation valve to the boiler before removing any water components.

User checks:

  • Check that water pressure at taps is normal.
  • Turn hot tap fully on to ensure adequate flow demand.

Engineer checks:

  • Isolate and remove the DHW flow sensor/turbine assembly.
  • Inspect for debris, limescale, or damage; clean and descale as necessary.
  • Check the inlet filter screen and clean.
  • Test the sensor output (e.g., pulses) to the PCB when water flows.
  • Replace the DHW flow sensor assembly if faulty.

Restoring correct flow sensing will usually clear E16 faults.

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Repair Difficulty

Medium 3/5

Required Part

DHW Flow Sensor / Turbine
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