Vaillant · ecoTEC exclusive
F.78 boiler fault code
ecoTEC exclusive combi
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Renting? Report it to your landlord or housing provider first. They are responsible for gas safety and boiler repairs, and the repair should not cost you.
What F.78 means
F.78 indicates DHW outlet sensor interruption at an external controller. The manual warns that some shared-table codes may not be visible on every product variant.
Safe check
Read and note the displayed code. Do not open, adjust or reset the boiler. Contact a Gas Safe registered engineer for diagnosis.
When to contact an engineer
The displayed fault remains or returns; arrange diagnosis by a Gas Safe registered engineer.
Safety notice
A boiler fault code alone is not a gas or carbon-monoxide emergency. If you smell gas, a CO alarm sounds, anyone feels unwell, or there is an unsafe flame, leave and call 0800 111 999 from outside.
Source and provenance
- ecoTEC exclusive combi Installation and Maintenance Instructions · 0020193968_05 · Appendix E, F.78, printed p. 57
installation and maintenance instructions
0020193968_05