BoilerFaultCodesVaillant d.24 Fault Code
Also written as D24 — same fault.
The Vaillant d.24 fault code means: your boiler is currently reporting whether the internal water pressure switch is active or inactive, which is part of its normal checking process but may indicate an issue if the boiler stops working.. It appears on 24 Vaillant models in our database.
Technical description: Status of the pressure monitor (off=Not switched, on=Switched)
DIY fix possible
Check the central heating pressure gauge on the front of the boilerIf the pressure is below 1.0 bar, use the external filling loop to top it up to 1.5 barEnsure all radiator valves are open and not blocked by air
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like d.24: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Vaillant models that show the d.24 fault code
Click a model for the full fault code list and model-specific repair notes.
- ecoFIT Pure 418 Repair: £0-120
- ecoFIT Pure 425 Repair: £80-160
- ecoFIT Pure 825
- ecoFIT Pure 830
- ecoFIT Pure 835 Repair: £0-120
- ecoMAX Repair: £250-450
- ecoMAX 613 Repair: £150-300
- ecoMAX 618 Repair: £150-300
- ecoMAX 622 Repair: £150-300
- ecoMAX 635 Repair: £150-300
- ecoMAX 824/2 E Repair: £150-300
- ecoMAX 828/2 E Repair: £150-300
- ecoMAX 835 E Repair: £150-300
- Ecomax Condensing 600/800 series 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: £150-250
- Turbomax Plus Repair: £150-£300
- Turbomax Plus 824/828E
- Turbomax Plus 828 Repair: £60-140
- Turbomax Plus 828 E
- Turbomax Plus VUW 242E
- Turbomax Plus VUW 242EH
Source
Vaillant d.24 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 Ecomax Condensing 600/800 series manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026