High
Lock-out signal lamp red (ON) on Biasi Riva Compact HE M96a

Your boiler is failing to detect the flame after lighting, causing it to shut down for safety even though the burner briefly ignites.

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

The burner doesn’t light up, the ignition sparks continue and the boiler blocks. Pressing the reset push-button the boiler starts the ignition cycle again. The burner lights up, the ignition sparks continue and the boiler blocks again.

From this model's manual
Verified against the Riva Compact He M96a System Service 2008 installation & service manual.
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 Lock-out signal lamp red (ON): 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 guides you might find useful

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →