Saunier Duval Intermittent Electrical or Sensor Fault

Boiler frequently locks out and needs manual reset, with varying fault codes over time

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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

Loose PCB connectors, Intermittent NTC sensor, Moisture on PCB or connectors, Failing main PCB

How to Fix / Troubleshooting

Safety first: Isolate power before touching internal components.

Steps to check:

  • Remove the front cover and inspect for signs of water ingress or corrosion on the PCB and connectors.
  • Gently press all plug-in connectors on the PCB and sensors to ensure they are fully seated.
  • Check that the condensate trap and internal pipework are not leaking onto electrical parts.
  • Record the fault codes that appear to help a professional diagnose patterns.
  • If lockouts continue, a heating engineer should test sensors and possibly replace the PCB.

Warning: Do not spray cleaning fluids on the PCB; this can cause further damage.

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Repair Difficulty

Hard 4/5

Required Part

Main Control PCB / NTC Sensors
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