BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Locate the filling loop (a flexible metal hose) underneath your boiler.Open the small valve(s) on the loop to allow water into the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (between 1.0 and 1.5 bar).Close the valve(s) tightly and ensure the boiler resets.
Your boiler has stopped working because the amount of water circulating inside the heating system has dropped too low.
Locate the filling loop (a flexible metal hose) underneath your boiler.Open the valves on the filling loop to allow cold mains water into the system.Watch the pressure gauge on the front of the boiler until the needle reaches between 1.0 and 1.5 bar.Close both valves tightly and remove the filling loop if required by your specific model.
Your boiler has lost its ability to measure the temperature of the water moving through your heating system, so it has shut down as a precaution to prevent overheating.
Full guide for F.00Your boiler has lost the ability to measure the temperature of the water coming back into it, so it has turned itself off as a safety precaution.
Full guide for F.01Your boiler has stopped working because it is unable to accurately measure the temperature of the water inside the system due to a faulty electrical connection or sensor.
Full guide for F.10Your boiler is struggling to read the temperature of the water returning to it, which causes it to stop working to avoid potential damage.
Full guide for F.11on the Vaillant Home Combi
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Vaillant shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
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