BoilerFaultCodesPotterton E85740 Fault Code
The Potterton E85740 fault code means: your boiler has detected an issue with the sensor that confirms the flame is safely lit, causing the system to shut down for safety.. It appears on 1 Potterton model in our database.
Technical description: Ionization Probe & lead c/w Gasket & 2 screws
What causes the Potterton E85740 fault?
This fault occurs when the boiler's control system cannot detect a steady flame, causing it to shut down for safety. The most common reason is a buildup of carbon or debris on the ionization probe, which prevents it from sending a signal, or a failure in the electrical lead connecting the probe to the main board.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Potterton models that show the E85740 fault code
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Source
Potterton E85740 fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026