BoilerFaultCodesThe 6 most common faults
01
C1 High Engineer
Your boiler is struggling to push air through the system to burn fuel safely, so it has stopped working to protect itself.
Full guide for C102
C6 High Engineer
Your boiler has detected that the internal fan responsible for moving air and burnt gases is spinning faster than it should, causing the system to stop working for safety reasons.
Full guide for C603
E2 High Engineer
Your boiler has lost the ability to accurately measure the temperature of the water flowing through it, so it has shut down as a precaution to prevent overheating.
Full guide for E204
E9 High Engineer
Your boiler has detected that it is dangerously overheating and has automatically shut itself down to prevent internal damage.
Full guide for E905
EA High Engineer
Your boiler is failing to light the internal flame, which means it cannot provide you with any heating or hot water.
Full guide for EA06
A7 High Engineer
Your boiler is struggling to accurately detect the temperature of the water being used, which will likely prevent you from having hot water until it is fixed.
Full guide for A7on the Worcester Bosch Ri 25 HE
Fan assemblyAir pressure switchWiring harnessPrinted Circuit BoardPrinted Circuit Board (PCB)NTC 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 Worcester Bosch 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