BoilerFaultCodesPotterton E03 Fault Code
The Potterton E03 fault code means: your boiler has shut down because it is unable to safely discharge exhaust fumes or has detected that the flue system is overheating.. It appears on 2 Potterton models in our database.
Technical description: Flow temperature abnormally high. Check pump, 3-way valve & CH system pressure. Replenish system, adjust pump speed & bleed air
What causes the Potterton E03 fault?
This fault occurs when the boiler's internal sensors detect that harmful exhaust gases are not being cleared away correctly or that the flue is getting too hot. The most common reasons include a blockage in the flue pipe, a failing fan that cannot push the fumes out, or a sensor that has become faulty and is giving a false reading.
This fault can sometimes occur during period of high winds, as strong gusts can create back-pressure in the flue that interferes with the air pressure switch.
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 E03 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton E03 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