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Viessmann display codes
Checked against its sources: Updated
Viessmann fault codes are mostly not explained to users: the Vitodens manuals read show a fault number but tell you to note it for the contractor, and define only a few displays such as CL and E3.12 The user manuals read don't list other numbers.
- Covers
- Viessmann Vitodens 050-W and 100-W/111-W, GB issues of 2026
- You
- Note the code, reset a burner lockout once, bleed radiators, and top up or call if pressure is below 1.0 bar.
- A professional
- Everything else. The manual says "Do not open the appliance." and "Do not remove casings."
1 Displays the manuals explain
| Code or display | What the Viessmann manual says | Which manual, page | What the Viessmann manual lets you do |
|---|---|---|---|
| CL with flashing warning triangle | Burner locked out; burner doesn't start | 050-W (05/2026) pp25, 28-291 | Reset; notify the contractor if it recurs |
| Burner symbol with flashing fault number | Burner fault | 100-W (03/2026) pp29-30, 332 | Note the number, reset; notify the contractor if it recurs |
| Fault menu (Er) | Lists fault messages; no numbers are defined | 050-W pp24, 28-291; 100-W p292 | Tell the contractor the code. OK only closes the message |
| E3 (shown "E 3" on 100-W) | Holiday program or holiday at home on, via the app | 050-W p281; 100-W p332 | Check in the app, change or switch off |
| E10 | Connection to the home network can't be established | 050-W p201 | Check the router connection and network password |
| E12 | Connection to the server can't be established | 050-W p201 | Try the connection again later |
| "- - -" flashing three times | Emissions test mode not possible, low flow or low heat draw; not a fault you need to act on | 050-W p261; 100-W p312 | Nothing needed |
The 050-W note says these codes appear in parts, first "E1" and then "0", so read the whole sequence before writing it down.1
2 How the reset works
Note the fault number first. Then press the up and down keys for about 4 seconds; a rotating bar shows the reset has started.1 Closing the fault display for now, or pressing OK on a message, is not a repair.1 Viessmann's warning is strong: "Do not reset the burner several times in quick succession", because faults left unrectified can have life-threatening consequences.1 Try once and then call the contractor.
3 Other checks in the manual
Below 1.0 bar the manuals say "Please top up with water or notify your heating contractor", but give no fill method or upper figure, so ask the contractor; see boiler pressure.12 For air, the same tables say to bleed radiators.12
4 Where these manuals don't fit UK advice
The GB-issue 050-W manual cites German rules and maintenance "at least every 2 years".1 That shouldn't be used as UK servicing guidance; see boiler service. The gas section gives no UK emergency number, so use the gas entry instead. The word condensate doesn't appear in the text of either manual, so there is no maker's method for a frozen pipe.
5 What wasn't covered
Only these two user documents, from Viessmann's UK library, were read, the 100-W in fewer places than the 050-W.3 Other Vitodens models weren't read and may differ.
Sources
- Operating instructions for the system user, Vitodens 050-W, 6173895 GB 05/2026, Viessmann read 3 November 2026.
- Operating instructions for the system user, Vitodens 100-W/111-W, 6167584 GB 03/2026, Viessmann read 3 November 2026.
- Viessmann UK technical documents library, ViBooks read 3 November 2026.