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

Your boiler is failing to detect that the flame has lit, causing it to shut down for safety reasons to prevent a build-up of unburned gas.

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, the ignition sparks continue and the boiler locks. By pressing the reset push-button the boiler starts the ignition cycle. The burner lights, the ignition sparks continue and the boiler locks again.

From this model's manual
Verified against the Riva Compact He C2 Service 2007 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 →

Avoid the next call-out bill

A cover plan would handle faults like Lock-out signal lamp 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