BoilerFaultCodesPotterton E85802 Fault Code
The Potterton E85802 fault code means: your boiler has suffered an electrical failure where an internal fuse has blown, meaning the system cannot power its main components to provide heat or hot water.. It appears on 1 Potterton model in our database.
Technical description: Fuse 3.15A “Slow Blow”
What causes the Potterton E85802 fault?
This fault occurs when an electrical surge or a component failure causes the boiler's internal safety fuse to blow, cutting off power to prevent further damage. The most common reason for this is an aging internal pump that has seized or short-circuited, drawing too much current and overloading the system's delicate electronics.
This issue is more frequent at the start of autumn, as pumps that have sat idle during the summer are more likely to seize or fail when first switched back on for heating.
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 E85802 fault code
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Source
Potterton E85802 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