High
Lockout (Red) flashing on Potterton Performa SL HE 9 2

Your boiler has sensed it is getting too hot and has shut itself down as a safety precaution.

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

Overheat condition occurs

Shared across the Performa 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 happens when water inside the boiler reaches a temperature that is no longer safe, triggering an automatic shutdown to prevent damage. It is usually caused by a pump failure preventing water from moving away from the heat exchanger, or a build-up of sludge and debris that blocks the flow. In some cases, a faulty sensor might also incorrectly signal that the system is overheating.

This issue often surfaces in autumn when the heating is turned on for the first time after summer, as internal pump parts can seize during long periods of inactivity.

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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Avoid the next call-out bill

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All 17 fault codes on the Performa SL HE 9 2

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

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