BoilerFaultCodesFirebird E1 Fault Code
The Firebird E1 fault code means: your boiler's internal temperature sensor has stopped sending the correct signal, meaning the system doesn't know how hot the water is and has shut down for safety.. It appears on 8 Firebird models in our database.
Technical description: Control thermistor fault
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Firebird models that show the E1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Firebird E1 fault code information on this page is sourced and cross-checked against the official Firebird service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026