BoilerFaultCodesThe 6 most common faults
Your boiler has stopped because the water pressure inside your heating system has dropped too low to operate safely.
Locate the external filling loop, which is usually a flexible silver braided hose with one or two valves located underneath your boiler.Slowly open the valve(s) to allow mains water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Close the valve(s) tightly to ensure no water continues to leak into the system.
Your boiler has detected low water pressure and is currently sitting in a waiting period to protect itself from damage.
Locate the external filling loop (a flexible silver hose) beneath the boiler.Open the filling valve slowly until the pressure gauge reads between 1.0 and 1.5 bar.Close the valve tightly and check for any leaks.
Your boiler is preventing itself from firing up because it cannot detect enough water flowing through the system to heat your home safely.
Check that all your radiator valves are fully openEnsure your system pressure is at the recommended level (usually 1.0 to 1.5 bar) using the filling loopCheck that any external zone valves or system bypass valves are not stuck or obstructing flow
Your boiler has detected that there is not enough water pressure circulating through your heating system to operate safely.
Locate the filling loop, which is a silver braided hose with one or two valves located underneath the boiler.Open the valve(s) slowly to allow mains water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Close the valve(s) firmly and ensure no water is leaking from the connection.
Your boiler is struggling because the pipe that carries away waste water is blocked, preventing the system from clearing itself safely.
Full guide for F.028Your boiler is unable to drain the water it produces during normal operation, which is causing it to automatically shut down for safety.
Full guide for F.029on the Vaillant Turbomax 242/282 1E
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