BoilerFaultCodesVaillant E13 Fault Code
The Vaillant E13 fault code means: your boiler has automatically shut down because the internal water pressure has dropped too low to operate safely.. It appears on 2 Vaillant models in our database.
Technical description: Water deficiency error – Appliance blocked
DIY fix possible
Locate the filling loop (usually two valves connected by a silver braided flexible hose underneath the boiler).Open both valves slowly to let mains water into the heating system.Watch the pressure gauge on the front panel until the needle reaches between 1.0 and 1.5 bar, then firmly close both valves.
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Vaillant models that show the E13 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vaillant E13 fault code information on this page is sourced and cross-checked against the official Vaillant service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026