BoilerFaultCodesThe 6 most common faults
01
E164 High DIY-safe
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
What to try first
Locate the filling loop (usually a silver braided hose with one or two valves) under your boiler.Gradually open the valve(s) to allow mains water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close the valve(s) tightly and reset the boiler.
02
E20 High Engineer
Your boiler has lost the ability to accurately measure the temperature of the water leaving it, so it has safely shut itself down to prevent overheating.
Full guide for E2003
E128 High Engineer
Your boiler has detected that the flame inside has gone out unexpectedly while it was trying to heat your water or home.
Full guide for E12804
E129 High Engineer
Your boiler is struggling to push air through the system correctly, which is preventing it from lighting safely.
Full guide for E12905
E133 High Engineer
Your boiler is failing to light because it cannot detect a flame, meaning you currently have no heating or hot water.
Full guide for E13306
E151 High Engineer
Your boiler's internal computer is experiencing a communication fault, which has caused it to shut down for safety.
Full guide for E151on the Potterton Sirius FS
Filling loopPressure relief valvePressure gaugeNTC SensorWiring HarnessIgnition electrode
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