Common problems guide

The most common Saunier Duval Xeon 40ff problems

The faults most likely to send a Saunier Duval Xeon 40ff into lockout — with plain-English causes, what to check first, estimated repair costs and whether you need a Gas Safe engineer.

4 documented codes
4 most common
0 DIY-safe checks
4 engineer needed

The 4 most common faults

Call a Gas Safe engineer if…

  • You can smell gas or see signs of a leak
  • The Saunier Duval shows an Emergency or High severity code
  • The boiler keeps locking out after repeated resets
  • You've tried the DIY checks and the fault hasn't cleared
  • There's visible water leaking from the boiler
  • The flame is yellow or orange instead of blue
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See the full 4-code list for the Saunier Duval Xeon 40ff

Related guides

Boiler losing pressure → No hot water → When to replace → Symptom checker →