High Lockout
49 on Ideal Mexico CF3 40 & 50

Your boiler has successfully lit its pilot light, but the main burner is failing to ignite because it is not receiving the main supply of gas.

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.

Technical description

PILOT LIT BUT NO MAINS GAS

What causes this fault?

This fault occurs when the boiler successfully lights the small pilot flame but fails to transition to the main burner to heat your home. It is physically caused by a lack of gas flow to the main burner, often due to a faulty gas valve or a blockage in the pilot assembly that prevents the control board from seeing a strong enough signal to release the main gas supply.

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 →

Related fault codes

47View →48View →

Related guides you might find useful

Pilot light keeps going out

Older boilers — thermocouple, draught, gas supply.

Read →

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →