BoilerFaultCodesThe 6 most common faults
01
27 High DIY-safe
Your boiler has detected that water is either not moving around the system correctly or that the pressure of the water inside the unit is too low to run safely.
What to try first
Locate the pressure gauge on the front of your boiler.Check if the needle is below the 1 bar mark.Use the filling loop (a metal braided hose or key under the boiler) to slightly open the valves and top up the system until the needle reaches 1.5 bar.
02
Pump Fault or Low Pressure High DIY-safe
Your boiler has stopped working because the water pressure inside the system is too low or the internal water pump has failed to move heat around your home.
What to try first
Check your boiler's pressure gauge; if it is below 1 bar, top it up using the filling loopOnce the pressure is between 1 and 1.5 bar, switch the boiler off and back on at the mains to reset itIf the pressure was normal, turn the heating thermostat up to check if the pump hums
03
24 High Engineer
Your boiler has stopped working because it cannot light its burner properly, which is often caused by a blockage in the pipe that drains away waste water.
Full guide for 2404
25 High Engineer
Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent damage.
Full guide for 2505
26 High Engineer
Your boiler is currently unable to safely remove waste gases, so it has shut itself down to prevent any risk to your home.
Full guide for 2606
28 High Engineer
Your boiler has detected an issue with the sensor that monitors the temperature of the exhaust gases, causing it to stop working for your safety.
Full guide for 28on the Potterton Performa 24i HE
Central heating pumpPressure relief valvePressure sensorCondensate trapIgnition electrodeGas valve
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 Potterton 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