How much does it cost to fix Grant error code RED blinking?

Typical repair cost for the Grant RED blinking fault is £120-220 including labour.

RED blinking High

Grant RED blinking Fault Code

Q: What does the Grant RED blinking fault code mean?

Your boiler is failing to start because it detects light inside the combustion chamber when it should be completely dark, preventing it from igniting safely.

Also written as REDBLINKING — same fault.

The Grant RED blinking fault code means: your boiler is failing to start because it detects light inside the combustion chamber when it should be completely dark, preventing it from igniting safely.. It appears on 5 Grant models in our database.

Technical description: The burner goes into lockout mode before or during the pre-purging. The UV sensor sees extraneous light. Eliminate the extraneous light.

Typical repair cost £120-220 (including labour)

Engineer required

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

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Grant models that show the RED blinking fault code

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

Source

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

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