Detection Lockout High

Ideal Detection Lockout Fault Code

Also written as DETECTIONLOCKOUT — same fault.

The Ideal Detection Lockout fault code means: your boiler has stopped working because it cannot detect a flame, meaning it has safely shut down to prevent gas from flowing without being burned.. It appears on 2 Ideal models in our database.

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: The description indicates this is displayed when there is a failure in the flame safety device, specifically if the main burner is extinguished or the gas inlet cock is turned off.

What causes the Ideal Detection Lockout fault?

This fault occurs when the boiler's control system fails to confirm that a flame has been successfully lit after a sequence of attempts. The most common reasons include a lack of gas reaching the burner, worn-out sparking electrodes that fail to ignite the fuel, or a dirty sensor that can no longer 'see' the flame even if it is actually present.

Typical repair cost £100-280 (including labour)

DIY fix possible

Check that your gas emergency control valve (usually by the meter) is in the 'on' positionCheck if other gas appliances in your home, such as a hob, are working correctlyPress the reset button on the front control panel to see if the boiler restarts

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Ideal models that show the Detection Lockout fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Ideal Detection Lockout fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026