How much does it cost to fix Grant error code 0 4?

Typical repair cost for the Grant 0 4 fault is £250-500 including labour.

0 4 Medium

Grant 0 4 Fault Code

Q: What does the Grant 0 4 fault code mean?

Your boiler is warning you that the water in your area is extremely hard, which causes significant scale build-up inside the internal components and will eventually prevent the unit from heating water efficiently.

Also written as 04 — same fault.

The Grant 0 4 fault code means: your boiler is warning you that the water in your area is extremely hard, which causes significant scale build-up inside the internal components and will eventually prevent the unit from heating water efficiently.. It appears on 1 Grant model in our database.

Technical description: Very hard <370 mg/l calcium carbonate

Typical repair cost £250-500 (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 0 4 fault code

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

Vortex Blue Repair: £250-500

Source

Grant 0 4 fault code information on this page is sourced and cross-checked against the official Grant service / installation manuals for each affected model.

Grant Vortex Blue manual (PDF)

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