BoilerFaultCodesRavenheat E23 Fault Code
The Ravenheat E23 fault code means: your boiler has detected a fault with the sensor that monitors exhaust gases, and as a safety precaution, it will not operate until this is fixed.. It appears on 6 Ravenheat models in our database.
Technical description: Flue sensor damaged
What causes the Ravenheat E23 fault?
This fault occurs when the internal sensor responsible for monitoring the temperature of the exhaust gases becomes faulty or disconnected. The most common reason is natural wear and tear or heat damage to the sensor's thermistor, which prevents it from sending an accurate reading to the main control board. As a safety measure, the boiler shuts down to prevent any risk of the flue system overheating.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Ravenheat models that show the E23 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ravenheat E23 fault code information on this page is sourced and cross-checked against the official Ravenheat service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026