S.41
FAULT CODE
Vaillant
System Pressure Too High (>2.8 bar)
Medium Severity
Engineer Required
Status code: The system water pressure has exceeded 2.8 bar. The boiler is blocking for safety. This can be caused by the filling loop being left open or a faulty pressure relief valve.
Step-by-Step Fix Guide
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Step 1
Do NOT add more water to the system
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Step 2
Check that the filling loop is fully closed
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Step 3 Engineer only
If pressure remains above 2.8 bar, call a Gas Safe engineer — the pressure relief valve may need to be operated or the expansion vessel may have failed
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.