BoilerFaultCodesIntergas E03 Fault Code
The Intergas E03 fault code means: your boiler has shut down because its internal temperature sensors have detected that the exhaust gases are getting too hot, which could damage the system.. It appears on 6 Intergas models in our database.
Technical description: Flue gas temperature exceeded
What causes the Intergas E03 fault?
This fault occurs when the internal sensors detect that the waste gases leaving your boiler are significantly hotter than they should be, triggering a safety shutdown to prevent internal damage. The most common reason is a buildup of debris or limescale inside the heat exchanger, which prevents heat from being transferred to your water and instead sends it out through the flue. It can also be caused by a faulty sensor giving an incorrect reading or a lack of proper water flow through the system.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Intergas models that show the E03 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Intergas E03 fault code information on this page is sourced and cross-checked against the official Intergas service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026