High
E42 on Potterton Powermax HE

Your boiler's computer brain has encountered a serious internal error and can no longer control the heating or hot water safely.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

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

Shared across the Powermax HE range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this 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.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

E40View →

All 59 fault codes on the Powermax HE

Seeing a different code? Every code this model can display, in one place.

1619A (number)A01A02A03A04A05A07A09-12A15A18A19A20A33A40A41b52c80E01E03E04E06E07E08E13E13/16/19E20E21E22E29E30E31E32E33E40E41p < 0.5P 0.4P 0.9p 1.5P 3.1P 3.1 or higherP0.1-0.4P0.1-0.4 barP0.5-0.9P0.5-0.9 barP1.0-2.9P1.0-2.9 barP3.0-3.5P3.0-3.5 barP19P20RED NEONSafety LOCK-OUTSafety shut-downt80U60

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