High
P0.5-0.9 bar on Potterton Powermax HE

Your boiler has detected that the water pressure is too low, which prevents the system from running safely and efficiently.

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

Water pressure in CH system low

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 there is not enough water in your heating system to maintain the required pressure for operation. The most common reason is a slow leak from a radiator valve or pipework, though it can also happen if air was recently bled from your radiators without the system being topped back up.

This issue is more frequent in autumn when homeowners turn their heating back on for the first time and discover that pressure has dropped over the summer months.

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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Related fault codes

All 59 fault codes on the Powermax HE

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

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