BoilerFaultCodesVaillant N.270 Fault Code
Also written as N270 — same fault.
The Vaillant N.270 fault code means: your boiler has detected that hot water is not transferring correctly through its internal heating system, so it is limiting its own performance to prevent further stress.. It appears on 3 Vaillant models in our database.
Technical description: The temperature spread via the secondary heat exchanger (heating flow – domestic hot water connection) is too high. The unit switches from regulating to controlling until the cause has been eliminated by customer service.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Vaillant models that show the N.270 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vaillant N.270 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 7 July 2026