BoilerFaultCodesThe 6 most common faults
Your boiler has temporarily paused because the water pressure is too low or the water isn't circulating properly between the pipes.
Check the pressure gauge on the front of your boiler to see if it has dropped below 1 bar.Use the filling loop underneath your boiler to top up the system pressure until it reaches between 1 and 1.5 bars.Reset the boiler using the reset button if it does not restart automatically.
Your boiler has automatically shut down because the internal water pressure has dropped too low to operate safely.
Locate the filling loop valves underneath your boiler or near your hot water cylinder.Open the valves slowly to let mains water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close both valves tightly and reset the boiler using the reset button.
Your boiler has detected that the water pressure isn't rising correctly when the internal pump starts up, which usually points to low system pressure, trapped air, or a faulty sensor.
Check the system pressure gauge on the front of the boiler to see if it is below 1 bar.Use the filling loop underneath the boiler to top up the pressure to between 1 and 1.5 bars.Restart or reset the boiler to clear the fault code.
Your boiler's fan is attempting to spin, but the electronic control board isn't receiving the correct signal back to confirm it is working properly.
Full guide for S.26Your boiler is pausing because its internal air-flow system is not operating at the correct speed to run safely.
Full guide for S.32Your boiler has detected that a safety flap in the exhaust pipe is stuck in the closed position, which prevents the unit from venting fumes safely and stops it from starting up.
Full guide for S.42on the Vaillant ecoFIT Pure 435
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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