BoilerFaultCodesVaillant D.75 Fault Code
Also written as D75 — same fault.
The Vaillant D.75 fault code means: your boiler has stopped heating your hot water tank because it has been running for too long without reaching the target temperature, likely due to a sensor or flow issue.. It appears on 17 Vaillant models in our database.
Technical description: Max.chargingtimefordomestichotwatercylinderwithoutindependentcontrolsystem
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Vaillant models that show the D.75 fault code
Click a model for the full fault code list and model-specific repair notes.
- ecoFIT Pure 418 Repair: £120-450
- ecoFIT Pure 425 Repair: £100-250
- ecoFIT Pure 825 Repair: £150-350
- ecoFIT Pure 830 Repair: £150-250
- ecoFIT Pure 835 Repair: £100-350
- ecoTEC plus VU GB 656/4-5 A Repair: £150-300
- ecoTEC sustain Repair: £150-300
- Home Combi 25 Repair: £120-250
- Home Combi 30 Repair: £120-250
- Home Combi 35 Repair: £120-250
- Turbomax 824/828 Repair: £120-250
- Turbomax Plus Repair: £120-250
- Turbomax Plus 824/828E
- Turbomax Plus 828 Repair: £120-250
- Turbomax Plus 828 E Repair: £120-250
- Turbomax Plus VUW 242E Repair: £120-220
- Turbomax Plus VUW 242EH Repair: £120-250
Source
Vaillant D.75 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 835 manual (PDF)
- Vaillant ecoTEC plus VU GB 656/4-5 A manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026