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Vaillant fault and status codes
Checked against its sources: Updated
Vaillant fault codes defined in the user manuals read are mainly F.22 (low water) and F.28 (no flame at ignition); N codes mean limited running, and S codes report status.123 The 2006 issue adds a few more F numbers, and the user manuals read don't list others.4
- Covers
- Vaillant ecoTEC plus and ecoTEC pro issues named below, gas
- You
- Top up for F.22 as your manual says, reset for F.28 by your issue's method, and read S codes as information.
- A professional
- Every other F code, N codes, repeat faults, and on older issues purging air. A competent person means a Gas Safe registered engineer for gas work.
1 Fault and limp-home codes
| Code or display | What the Vaillant manual says | Which manual, page | What the Vaillant manual lets you do |
|---|---|---|---|
| F.022 (2023), F.22 (older) | "No/insufficient water in the product or the water pressure is too low"; on the pro, below 0.5 bar the boiler switches off and the display alternates F.22 and the pressure | ecoTEC plus 28.11.2023 p201; ecoTEC plus 26.05.2021 p102; ecoTEC pro 03.08.2017 p93 | Check the pressure and top up as that manual says. On 2023, F.22 clears by itself when pressure recovers (p14) |
| F.028 (2023) | Flame signal not detected during ignition; fault mode after five unsuccessful attempts | 2023 p201 | Check by looking whether the gas stopcock is open (if it isn't, don't turn it on or reset; ask an engineer); if it is, hold reset over 3 seconds, maximum 3 repetitions; then a competent person |
| F.28 (2017, 2021) | Fault mode after three unsuccessful ignition attempts | 2021 p142; 2017 p123 | Fault clearance key for 1 second; a competent person after three attempts |
| F.28 with F.29 (VU 446, 606) | Burner failed after five ignition attempts | VU 446/606 pp16, 196 | Look at the gas stopcock without touching it; a closed one is for your gas supplier or an engineer, with no reset. If it's open, reset for one second. P16 says a competent person after three attempts, p19 prints up to five: use the lower |
| F.22, F.23, F.24 (2006) | System pressure too low: F.22 dry fire, F.23 or F.24 lack of water | 08/2006 p134 | The boiler restarts only once the system is filled |
| F.28, F.29 (2006) | Burner failed to ignite after five attempts | 08/2006 p134 | Hold reset for one second; installer or Vaillant after three attempts |
| F.32 (2006) | Fan not working properly; appliance switches off | 08/2006 p134 | Quote the code to Vaillant or your installer |
| N.xxx | Limp-home codes: the system can still run safely | 2023 p161 | Contact a competent person to have the fault fixed |
2 Status codes
| Code | What the Vaillant manual says | Which manual, page | What the Vaillant manual lets you do |
|---|---|---|---|
| S.000 | No demand for heating | 2023 p191 | No step printed |
| S.002, S.003, S.004 | Heating: pump pre-run; ignites; burner on | 2023 p191 | No step printed |
| S.006, S.007, S.008 | Heating: fan overrun; pump overrun; burner anti-cycling time | 2023 p191 | No step printed |
| S.012, S.013, S.014, S.016, S.017 | Hot water draw-off: pump pre-run; ignites; burner on; fan overrun; pump overrun | 2023 p191 | No step printed |
| S.020 | No demand for cylinder charging | 2023 p201 | No step printed |
| S.022, S.023, S.024, S.026, S.027, S.028 | Cylinder charging: pump pre-run; ignites; burner on; fan overrun; pump overrun; anti-cycling | 2023 p201 | No step printed |
| S.031, S.034 | Heating deactivated, no hot water demand; frost protection active | 2023 p201 | No step printed |
| S.00 to S.08, S.14, S.22, S.24, S.34 (two digits) | Same states on older boilers | 2021 p132; 2017 p123 | No step printed |
| S.10, S.20 | Hot water requirement | 2021 p132; 2017 p123 | No step printed |
| S.31, S.46 | Summer mode active; comfort protection, flame loss at minimum load | 2021 p132; 2017 p123 | No step printed |
The 2006 instructions (p12) and the VU 446/606 guide (pp18-19) carry their own S lists, adding for example S.30 for a room thermostat with no heating demand and, on the VU 446/606, S.85 for a low water flow service message.46
3 How the reset works on each issue
Look at the date on your manual. The 2023 ecoTEC plus says hold reset for more than three seconds, maximum three repetitions.1 The 2021 ecoTEC plus and 2017 ecoTEC pro say press the fault clearance key for one second, then a competent person after three attempts.23 The 2006 instructions say hold reset for one second, then your installer after three attempts.4 Try once; the printed number is a ceiling.
4 Where the sources differ
Vaillant's F22 web page says fixing the fault "should be left to an expert" and to call an installer, while the manuals tell the user to top up.5 This entry follows the manuals, for the issue named, and only for a user comfortable with repressurising. Purging differs too: the 2023 issue allows the user to purge, older issues leave it to a competent person.12 Top-up figures also differ by date, so check your manual's pressure figures.
5 What wasn't covered
The manuals don't describe thawing a condensate pipe; they say to have a fault in it fixed by a competent person.1 If you smell gas, follow the gas entry.
Sources
- Vaillant operating instructions, ecoTEC plus VU/VUW/VUI ..CS/1-5 (N-GB), 0020308119_03, 28.11.2023, Vaillant read 3 November 2026.
- Vaillant operating instructions, ecoTEC plus VU, VUW, VUI ..6/5-5, 0020245033_02, 26.05.2021, Vaillant read 3 November 2026.
- Vaillant operating instructions, ecoTEC pro VUW 246/5-3, 286/5-3, 0020244996_01, 03.08.2017, Vaillant read 3 November 2026.
- Vaillant instructions for use, ecoTEC plus 612-637, 824-837 and ecoTEC pro 24, 28, 838402_04, 08/2006, p13, Vaillant read 3 November 2026.
- F22 fault code, Vaillant web page, not a manual read 3 November 2026.
- Vaillant operating instructions, ecoTEC plus VU 446/5-5, VU 606/5-5, 0020261390_01, date not printed in the copy read, Vaillant read 3 November 2026.