BoilerFaultCodesThe 6 most common faults
01
PILOT WILL NOT LIGHT High Engineer
Your boiler is failing to ignite because the small pilot flame that starts the heating process is not staying lit or will not spark.
Full guide for PILOT WILL NOT LIGHT02
NO OR LOW WATER FLOW RATE High Engineer
Your boiler is struggling to detect enough water flowing through it, which is preventing your hot water from working correctly.
Full guide for NO OR LOW WATER FLOW RATE03
LOW WATER TEMPERATURE High Engineer
Your boiler is struggling to heat the water to the correct temperature because there is an issue with how it manages its internal gas flow.
Full guide for LOW WATER TEMPERATURE04
NOISY HEATER High Engineer
Your boiler is struggling to process heat correctly, which is causing rattling or banging sounds and suggests internal components are dirty or clogged.
Full guide for NOISY HEATER05
HIGH WATER TEMPERATURE Emergency Engineer
Your boiler has detected that the water inside is getting too hot and has shut itself down to prevent overheating.
Full guide for HIGH WATER TEMPERATURE06
SMELL OF COMBUSTION PRODUCTS Emergency Engineer
Your boiler is leaking potentially dangerous exhaust gases into your home rather than sending them safely outside.
Full guide for SMELL OF COMBUSTION PRODUCTSon the Potterton Main Mersey Super
ThermocouplePiezo igniterPilot injectorDHW Flow SensorPlate Heat ExchangerWater Filter
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