How much does it cost to fix Grant error code 31.5?

Typical repair cost for the Grant 31.5 fault is £150-300 including labour.

31.5 High

Grant 31.5 Fault Code

Q: What does the Grant 31.5 fault code mean?

Your boiler has detected a communication error between its main control board and the internal display unit, preventing it from operating correctly.

Also written as 315 — same fault.

The Grant 31.5 fault code means: your boiler has detected a communication error between its main control board and the internal display unit, preventing it from operating correctly.. It appears on 1 Grant model in our database.

Technical description: 31.5

Typical repair cost £150-300 (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 31.5 fault code

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

Vortex Repair: £150-300

Source

Grant 31.5 fault code information on this page is sourced and cross-checked against the official Grant service / installation manuals for each affected model.

Grant Vortex manual (PDF)

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026