BoilerFaultCodesThe 6 most common faults
01
F.00 High Engineer
Your boiler has stopped heating because it is struggling to accurately read the temperature of the water flowing through its internal system.
Full guide for F.0002
F.01 High Engineer
Your boiler has stopped working because it is unable to accurately measure the temperature of the water returning to it from your radiators.
Full guide for F.0103
F.10 High Engineer
Your boiler has stopped working because it is unable to accurately measure the temperature of the water flowing through the system due to a connection fault.
Full guide for F.1004
F.11 High Engineer
Your boiler has detected a faulty connection in the pipework sensor that measures how hot your water is, which is preventing it from heating your home correctly.
Full guide for F.1105
F.20 High Engineer
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent any damage.
Full guide for F.2006
F.23 High Engineer
Your boiler has detected that the water flowing out is significantly hotter than the water returning, suggesting the internal pump is struggling to move water around your heating system properly.
Full guide for F.23on the Glow-worm Energy Regular
NTC Flow Temperature SensorWiring harnessReturn NTC thermistorFlow temperature sensorReturn temperature sensorNTC Temperature Sensor
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 Glow-worm 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