BoilerFaultCodesViessmann 299 Fault Code
The Viessmann 299 fault code means: your boiler's internal clock has lost track of the time or date, so timed heating and hot water schedules may not run correctly, but the boiler itself is usually still safe to use.. It appears on 13 Viessmann models in our database.
Technical description: Real-time clock fault
DIY fix possible
Check the date and time shown on the boiler's control panel and see whether they are wrong.Use the control dial and buttons to set the correct date, time and day of the week, following the menu in your user manual.Confirm your heating and hot water timer programmes are still correct, then switch the boiler off at the control panel for 30 seconds and back on to clear the message.
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Viessmann models that show the 299 fault code
Click a model for the full fault code list and model-specific repair notes.
- Vitodens 050-W B0HA-19 Repair: £90-250
- Vitodens 050-W B0HA-25 Repair: £90-250
- Vitodens 050-W B0KA-25 Repair: £90-250
- Vitodens 050-W B0KA-30 Repair: £90-250
- Vitodens 050-W B0KA-30-M Repair: £90-250
- Vitodens 050-W B0KA-35 Repair: £90-250
- Vitodens 100-W B1HF-11 Repair: £90-250
- Vitodens 100-W B1HF-19 Repair: £90-250
- Vitodens 100-W B1HF-25 Repair: £90-250
- Vitodens 100-W B1HF-32 Repair: £90-250
- Vitodens 100-W B1KF-26 Repair: £90-250
- Vitodens 100-W B1KF-30 Repair: £90-250
- Vitodens 100-W B1KF-35 Repair: £90-250
Source
Viessmann 299 fault code information on this page is sourced and cross-checked against the official Viessmann service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026