BoilerFaultCodesPotterton E04 Fault Code
The Potterton E04 fault code means: your boiler has shut itself down for safety because it tried to light several times but couldn't maintain a steady flame.. It appears on 2 Potterton models in our database.
Technical description: Flow sensor open circuit. Check cable/connections not damaged. Renew sensor/cable. Check connections on control
What causes the Potterton E04 fault?
This fault occurs when the boiler's control system fails to detect a consistent flame after several ignition attempts, causing it to shut down for safety. The most common reasons are a worn-out sensing probe that can no longer 'see' the flame, or a blockage in the internal drainage system that causes water to back up into the burner.
This issue is more frequent during very cold spells, as frozen external drainage pipes can prevent the boiler from clearing waste water, leading to a flame failure.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Potterton models that show the E04 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton E04 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 7 July 2026