How do I fix Baxi E78?

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

Baxi 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 using the filling loop (the silver braided tap) to about 1.2–1.5 bar
Press the reset button 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 Baxi fault codes

Baxi E119Low water pressure (below 0.5 bar).…Baxi E133Ignition failure — often a gas supply issue or a frozen cond…Baxi E160Fan fault or a flue blockage.…Baxi E168Power supply fault or system lockout.…

Baxi E78 — what it means

✅ Try these first — they're free

🔧 If that doesn't fix it

Other Baxi fault codes

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