S.10
FAULT CODE
Vaillant
Blocking: Anti-Cycle Control Active
Low Severity
DIY Check Possible
The anti-cycle timer is preventing the boiler from restarting immediately after a heating cycle. This is normal boiler behaviour, not a fault.
Step-by-Step Fix Guide
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Step 1
No action required — the boiler will restart automatically
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Step 2
If the boiler seems to never restart, call a Gas Safe engineer
Gas Safe Reminder
Work on gas appliances must be carried out by a Gas Safe registered engineer. The steps above cover safe checks a homeowner can perform - any internal component replacement requires a qualified professional. If in doubt, always call an engineer.