BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
Locate the filling loop, which is usually a flexible silver hose with one or two valves underneath the boiler.Gradually open the valve(s) to let mains water into the system while watching the boiler's pressure gauge.Stop filling once the needle reaches the green zone, typically between 1.0 and 1.5 bar, then tightly close the valve(s).
Your boiler has temporarily paused to protect itself because the water pressure inside the system is currently too low to run safely.
Locate the filling loop (a silver flexi-hose or two small valves) under the boiler.Gradually open the valves to let water into the system until the pressure gauge on the front reads between 1.0 and 1.5 bar.Close valves tightly and wait for the boiler to automatically restart.
Your boiler has stopped working because the water pressure inside the heating system has dropped below the required level.
Locate the filling loop, which is usually a silver braided hose under the boiler.Open the valves at both ends of the hose until you hear water flowing.Watch the pressure gauge on the front of the boiler until the needle reaches the green area (between 1 and 1.5 bar).Close both valves tightly and remove the filling loop if it is a detachable type.
Your boiler has stopped working because it has lost the connection to the sensor that monitors the temperature of the water flowing through your heating system.
Full guide for F.00Your boiler has lost the signal from the sensor that monitors the temperature of the water returning to the unit, causing it to shut down for safety.
Full guide for F.01Your boiler has stopped working because a sensor that measures the water temperature is providing an incorrect electrical signal that the system cannot understand.
Full guide for F.10on the Vaillant ecoTEC Pro 30
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