High
20 on Baxi Bahama 100

Your boiler is not detecting the water flow it needs to safely fire up, which may be caused by a blockage, an airlock, or a failing sensor.

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

20

From this model's manual
Verified against the Baxi/Baxi Bahama 100 installation & service manual, page 43.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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.

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like 20: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related fault codes

20View →

All 11 fault codes on the Bahama 100

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

101540608095Flame FailureGreen LightOrange LightRed Light

Related guides you might find useful

Hot water works but heating does not

On a combi it is usually the diverter valve. On a system boiler, the motorised valve.

Read →

How to bleed a radiator

Quarter turn on the valve, wait for water, then check the boiler pressure.

Read →

No hot water but heating works

Almost always a stuck diverter valve on a combi.

Read →