Viessmann Fault Codes
Comprehensive reference table of all Viessmann boiler error codes. Click any code for detailed troubleshooting steps.
Pro Tip
Check your boiler's digital display panel (usually behind a drop-down cover) to find the current active fault code.
| Error Code | Description | Applies To |
|---|---|---|
| F4 | No flame signal detected; often related to ignition, gas supply, or condensate. | Vitodens 100-W / 200-W |
F2 | Burner overheated; indicates pump failure or significant airlock in the heating system. | Vitodens 100-W / 200-W |
0B | Blocked burner; water flow insufficient, flow direction incorrect, or flow switch defective. | Vitodens 200 / 100-W |
0A | Fan speed is faulty; burner controls switch to safety lockout. | Vitodens 200 |
EB | Heat loss during calibration; technical fault with ionisation electrode or gas valve. | Vitodens 100-W / 200-W |
F9 | Fan speed is too low; safety lockout triggered. | Vitodens 100-W / 200-W |
10 | Outdoor temperature sensor short circuit; defaults to 0°C safety parameter. | Vitodens Series |
18 / D1 | Outdoor temperature sensor lead break; cable broken or disconnected. | Vitodens Series |
F6 / 58 / FE1 | Gas pressure switch fault; fan not at standstill during required phase or poor connection. | Vitodens Series |
D4 | Internal BUS fault / safety loop failure; Fuse F2 blown or fixed high limit has responded. | Vitodens 200-W |
50 / 51 / 59 | Domestic Hot Water (DHW) tank temperature sensor short-circuited or lead break. | Vitodens Series |
0C | Insufficient power supply; voltage drop forces PCB to block burner to protect components. | Vitodens 100-W |
0C | Ghost flame detected; flame signal detected after the burner has been told to switch off. | Vitodens 200 |
A4 | Internal circulation fault; pump struggling to move water due to airlock or severe restriction. | Vitodens 222-F |
38 | Water temperature sensor lead broken. | Vitodens 100-W |
FC | Faulty modulation valve control; faulty gas valve or vent system completely blocked. | Vitodens Series |
CC / F0 | Large voltage fluctuations detected; differential air pressure sensor fault or open circuit. | Vitodens 200 |
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