S.39
FAULT CODE
Vaillant
External Contact / Condensate Pump Blocking
Medium Severity
Engineer Required
Status code: An external switching contact (such as a condensate pump float switch) is preventing burner operation.
Cold Weather Note
In winter, check for a frozen condensate pipe before investigating the pump.
Step-by-Step Fix Guide
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Step 1
Check the condensate pump if fitted
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Step 2
Check for any external switching contacts connected to the boiler
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Step 3 Engineer only
Call a Gas Safe engineer if the cause is not obvious
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.