BoilerFaultCodesVaillant D.83 Fault Code
Also written as D83 — same fault.
The Vaillant D.83 fault code means: your boiler is providing a status update to show it is currently heating up the water for your taps.. It appears on 30 Vaillant models in our database.
Technical description: Burner start up in hot water mode
What causes the Vaillant D.83 fault?
This code appears when the boiler detects a demand for hot water and begins the ignition sequence to heat it. It is not actually a fault, but a status message indicating that the internal burner is firing up to provide water for your taps or shower. Once the water reaches the required temperature, the code will usually change or disappear.
DIY fix possible
This fault may be fixable without an engineer. Check your manual first.
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.83: 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.83 fault code
Click a model for the full fault code list and model-specific repair notes.
- Atmomax Repair: £90-180
- ecoFIT Pure 418
- ecoFIT Pure 425
- ecoFIT Pure 435
- ecoFIT Pure 825 Repair: £150-300
- ecoFIT Pure 830
- ecoFIT Pure 835
- ecoMAX
- ecoMAX 613
- ecoMAX 618
- ecoMAX 622
- ecoMAX 635
- ecoMAX 824E
- ecoMAX 828E
- Ecomax Condensing 600/800 series
- ecoMAX System 612
- ecoTEC
- ecoTEC 65kW
- ecoTEC plus aquaPLUS
- ecoTEC Pro / ecoTEC Plus Repair: £150-300
- ecoTEC sustain
- Home Combi
- Thermocompact
- Turbomax 824/828
- Turbomax Plus
- Turbomax Plus 824/828E
- Turbomax Plus 828
- Turbomax Plus 828 E
- Turbomax Plus VUW 242E
- Turbomax Plus VUW 242EH
Source
Vaillant D.83 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 835 manual (PDF)
- Vaillant ecoMAX manual (PDF)
- Vaillant ecoMAX System 612 manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026