BoilerFaultCodesVaillant D.76 Fault Code
Also written as D76 — same fault.
The Vaillant D.76 fault code means: your boiler is taking a short, programmed break to prevent itself from turning on and off too frequently, which protects the internal components from unnecessary wear.. It appears on 5 Vaillant models in our database.
Technical description: Remaining burner anti-cycling time in min
What causes the Vaillant D.76 fault?
This occurs when your boiler reaches its target temperature too quickly and needs to pause to prevent 'short-cycling,' which is like a car stalling in stop-start traffic. It usually happens because the heat produced by the boiler cannot be moved away fast enough, often because your radiators are already warm or some have been turned off. The boiler is simply waiting for the water in the system to cool down slightly before firing up again to work more efficiently.
This is most common during autumn and spring when the weather is mild and your home doesn't need the boiler's full heat output to stay warm.
DIY fix possible
Wait for 15 to 30 minutes for the countdown to finishCheck that your room thermostat is turned upEnsure all radiator valves are open to allow heat to dissipate
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Vaillant models that show the D.76 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vaillant D.76 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 27 April 2026