BoilerFaultCodesWorcester Bosch E9318 Fault Code
The Worcester Bosch E9318 fault code means: your boiler has detected that the connection to the sensor monitoring exhaust fumes has been broken or lost, causing the system to shut down for safety.. It appears on 1 Worcester Bosch model in our database.
Technical description: The flue gas temperature sensor contacts have been interrupted
What causes the Worcester Bosch E9318 fault?
This fault occurs when the boiler's control board can no longer communicate with the sensor that monitors the temperature of the exhaust gases. The most common reason is that the delicate electrical pins on the sensor have corroded or the wiring has vibrated loose over time. Because the boiler cannot verify that the fumes are at a safe temperature, it shuts down immediately to prevent damage to the internal plastic components.
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 →Worcester Bosch models that show the E9318 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch E9318 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026