S.33
FAULT CODE
Vaillant
Status: Fan Running — Pre-Purge
Medium Severity
DIY Check Possible
The fan is running to purge the combustion chamber before ignition. This is a normal pre-ignition safety step.
Step-by-Step Fix Guide
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Step 1
This is normal operation — the fan clears the combustion chamber before the burner fires
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Step 2
No action needed
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Step 3
If the boiler stays at this status and never ignites, there may be a fan or air pressure switch fault
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.