BoilerFaultCodesPotterton Lockout (Red) light is on Fault Code
Also written as LOCKOUTREDLIGHTISON — same fault.
The Potterton Lockout (Red) light is on fault code means: your boiler has stopped working because it couldn't safely ignite the flame after several attempts, so it has shut down to protect itself.. It appears on 1 Potterton model in our database.
Technical description: Boiler failed to light after five attempts (possibly due to air in the gas supply)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like Lockout (Red) light is on: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Potterton models that show the Lockout (Red) light is on fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton Lockout (Red) light is on fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026