E42 High

Potterton E42 Fault Code

The Potterton E42 fault code means: your boiler's computer brain has encountered a serious internal error and can no longer control the heating or hot water safely.. It appears on 1 Potterton model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Internal control error. Switch OFF/ON at mains isolator. Replace boiler control Part No. 5107535

What causes the Potterton E42 fault?

This fault occurs when the boiler's main electronic circuit board suffers a critical internal failure, meaning it can no longer process data or manage safety checks correctly. It is usually caused by the natural degradation of electrical components over time or a sudden power surge that damages the board's memory.

Typical repair cost £350-£550 (including labour)

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 E42 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Potterton E42 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