How much does it cost to fix Halstead error code Neon L4?

Typical repair cost for the Halstead Neon L4 fault is £120-250 including labour.

Neon L4 High

Halstead Neon L4 Fault Code

Q: What does the Halstead Neon L4 fault code mean?

Your boiler is failing to detect a flame, so it has purposefully shut itself down to prevent a gas leak.

Also written as NEONL4 — same fault.

The Halstead Neon L4 fault code means: your boiler is failing to detect a flame, so it has purposefully shut itself down to prevent a gas leak.. It appears on 1 Halstead model in our database.

Technical description: Flame sensing indicator

Typical repair cost £120-250 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Halstead models that show the Neon L4 fault code

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

Hero Repair: £120-250

Source

Halstead Neon L4 fault code information on this page is sourced and cross-checked against the official Halstead service / installation manuals for each affected model.

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