How do I fix Potterton E78?

Try first: Look at the pressure gauge — if it's under 1 bar, top up via the filling loop to about 1.2–1.5 bar; Press reset once. If that doesn't clear it, the likely part is Pressure sensor.

Potterton E78 Fault — What It Means & Fix Cost

⚠ This is the likely cause from the code — a Gas Safe registered engineer confirms it on site. If you can smell gas, stop and ring 0800 111 999.

✅ Try these first — they're free

Often clears it without a callout:

Look at the pressure gauge — if it's under 1 bar, top up via the filling loop to about 1.2–1.5 bar
Press reset once

🔧 If that doesn't fix it

The likely cause is one of these — the engineer confirms which:

Most likely part: Pressure sensor

Fixed repair price

£144

Inc. VAT — part & labour, no surprise callout fee. You only pay if you go ahead.

A vetted Gas Safe engineer who covers your postcode will call you back to arrange the repair. No callout fee — you only pay if you go ahead.

Other Potterton fault codes

Potterton E09Gas valve wiring or connection fault.…Potterton E10Outdoor (external) sensor fault.…Potterton E109Poor circulation around the system.…Potterton E110The boiler has overheated and tripped — often a stuck pump o…

Potterton E78 — what it means

✅ Try these first — they're free

🔧 If that doesn't fix it

Other Potterton fault codes

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