E05
Baxi Flow Temperature Sensor Fault

Heater locks out with E05, often after running for a short period; may be accompanied by high temperature readings.

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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

Faulty NTC flow temperature sensor on Baxi primary circuit, Loose or corroded sensor connector, Wiring fault between sensor and control PCB, Sensor removed from its pocket or not in good thermal contact

How to Fix / Troubleshooting

Safety: Isolate power before accessing internal components.

Steps:

  • Locate the flow NTC sensor: On most Baxi water heaters, the flow temperature sensor is clipped or screwed into a pocket on the primary flow pipe leaving the heat exchanger.
  • Check connection: Ensure the sensor plug is fully seated on the sensor and on the control PCB. Look for corrosion or moisture on the connector.
  • Inspect sensor placement: Confirm the sensor is properly inserted into its pocket or clipped firmly to the pipe with thermal paste if specified.
  • Basic resistance check (for skilled users with a multimeter): With power off and sensor disconnected, measure resistance across the sensor. Compare to Baxi’s temperature/resistance chart in the manual. Replace if readings are clearly out of range.

Professional help: If wiring and sensor appear fine, the control PCB may be faulty and should be tested/replaced by a qualified technician.

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Repair Difficulty

Medium 3/5

Required Part

Flow Temperature Sensor (NTC)
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