BoilerFaultCodesVaillant F.63 Fault Code
Also written as F63 — same fault.
The Vaillant F.63 fault code means: your boiler's internal computer has encountered a critical communication error and can no longer safely control the system, meaning your heating and hot water will be unavailable until a professional technician resolves the issue.. It appears on 45 Vaillant models in our database.
Technical description: EMC fault EMC or electronics defect
What causes the Vaillant F.63 fault?
This fault occurs when the boiler's central control board suffers an internal memory failure, meaning it can no longer store or read the vital settings needed to operate safely. It is typically caused by the steady degradation of electronic components over time or a sudden electrical surge that corrupts the board's permanent memory. Because the boiler no longer knows its own configuration, it shuts down immediately as a safety precaution.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A cover plan would handle faults like F.63: no call-out fees, no surprise bills.
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Vaillant models that show the F.63 fault code
Click a model for the full fault code list and model-specific repair notes.
- ecoFIT Pure 412 Repair: £250-450
- ecoFIT Pure 418 Repair: £250-450
- ecoFIT Pure 425 Repair: £250-450
- ecoFIT Pure 435 Repair: £250-450
- ecoFIT pure 612 Repair: £300-600
- ecoFIT pure 615 Repair: £300-600
- ecoFIT pure 618 Repair: £300-600
- ecoFIT pure 630 Repair: £300-600
- ecoFIT Pure 825 Repair: £250-450
- ecoFIT Pure 830 Repair: £250-400
- ecoFIT Pure 835 Repair: £250-450
- ecoFIT sustain 415 Repair: £300-600
- ecoFIT sustain 418 Repair: £300-600
- ecoFIT sustain 430 Repair: £300-600
- ecoFIT sustain 615 Repair: £300-600
- ecoFIT sustain 618 Repair: £300-600
- ecoFIT sustain 630 Repair: £300-600
- ecoFIT sustain 825 Repair: £300-600
- ecoFIT sustain 830 Repair: £300-600
- ecoFIT sustain 835 Repair: £300-600
- ecoMAX Repair: £250-£450
- ecoMAX 613 Repair: £250-£450
- ecoMAX 618 Repair: £250-£450
- ecoMAX 622 Repair: £250-£450
- ecoMAX 635 Repair: £250-£450
- ecoMAX 824/2 E Repair: £250-£450
- ecoMAX 828/2 E Repair: £250-£450
- ecoMAX 835 E Repair: £250-£450
- Ecomax Condensing 600/800 series Repair: £250-450
- ecoTEC exclusive Repair: £250-£450
- ecoTEC plus Repair: £250-£450
- ecoTEC plus VU GB 656/4-5 A Repair: £300-600
- ecoTEC pro Repair: £280-450
- ecoTEC sustain Repair: £280-450
- Home Combi 25 Repair: £250-450
- Home Combi 30 Repair: £250-450
- Home Combi 35 Repair: £250-450
- Home Regular 12
- Turbomax 824/828 Repair: £250-450
- Turbomax Plus Repair: £250-450
- Turbomax Plus 824/828E Repair: £250-450
- Turbomax Plus 828 Repair: £250-450
- Turbomax Plus 828 E Repair: £250-450
- Turbomax Plus VUW 242E Repair: £250-450
- Turbomax Plus VUW 242EH Repair: £250-450
Source
Vaillant F.63 fault code information on this page is sourced and cross-checked against the official Vaillant service / installation manuals for each affected model.
- Vaillant ecoFIT Pure 425 manual (PDF)
- Vaillant ecoFIT Pure 435 manual (PDF)
- Vaillant ecoFIT pure 630 manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026