We note the fault number
Model, fault number and, if possible, a photo of the display. It helps us plan the right parts.
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Wolf Error Codes
Your Wolf CGB-2 or FGB boiler shows a number such as 04, 05 or 12? Wolf numbers its faults: the table below gives the meaning of the most common ones. A fault number says which safety device or sensor has reacted, not what has to be replaced. Our engineers repair Wolf boilers 7 days a week, price given before the repair.
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WolfCGB-2, FGB…
Numbered faults01 to 21
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Wolf condensing boilers and their faults
The German manufacturer Wolf is less widespread than Vaillant or Viessmann in Belgium, but its wall-hung condensing gas boilers, especially the CGB-2 and the more compact FGB, are found in many renovated houses and flats. Wolf is also known for ventilation units and solar systems.
When the boiler stops, the control module shows a fault number. 04 (no flame at start) and 05 (flame lost during operation) are the most frequent; 01 and 07 point to overheating of the water or the flue gases; numbers between 12 and 16 concern temperature sensors.
Because Wolf parts are less common in Belgian wholesalers, a precise diagnosis matters even more: the engineer identifies the faulty part on the first visit and tells you the price and the time needed to obtain it.
Servicing a Wolf gas boiler
Most ignition and flame faults on Wolf boilers are linked to a worn electrode, a dirty burner or a siphon that no longer drains well. The yearly service treats these causes before they turn into a breakdown.
The technician cleans the heat exchanger and burner, tests the safety devices, analyses the combustion and gives you the service attestation.
Common Wolf error codes
The most frequent fault numbers on Wolf gas boilers. Type yours in the search box; if it is not here, the engineer will read it on site.
| Code | Meaning | What the technician checks |
|---|---|---|
| 01 | Safety temperature limiter (STB) tripped: overheating | Water circulation, pump, heat exchanger, safety limiter. |
| 04 | No flame formed at burner start | Gas supply, ignition and ionisation electrodes, gas valve. |
| 05 | Flame failure during operation | Gas pressure, ionisation, flue. |
| 07 | Flue gas temperature limiter tripped | Fouling of the heat exchanger, flue. |
| 11 | Flame detected before burner start (flame simulation) | Ionisation electrode, control unit. |
| 12 | Boiler flow sensor faulty | Flow sensor and its cable. |
| 13 | Flue gas sensor faulty | Flue gas sensor and its cable. |
| 14 | Hot water sensor faulty | Hot water sensor and its cable. |
| 15 | Outdoor sensor faulty | Outdoor sensor and its cable. |
| 16 | Return sensor faulty | Return sensor and its cable. |
| 20 | Gas valve 1 fault | Gas valve and its control. |
| 21 | Gas valve 2 fault | Gas valve and its control. |
Code not in this table: call us, our technician knows it.
Smell of gas? Do not touch any switch, open the windows, leave the house and call 112 from outside. For any other code, write it down and call us: the technician knows what to look at and brings the right parts.
What happens after your call
On-site diagnosis
The engineer measures gas pressure, ionisation and temperatures to confirm the cause.
Repair at the agreed price
The price is given before the repair. Afterwards you receive the job report and the invoice.
What our customers say
Where do we work?
Our heating engineers repair and service Wolf boilers all over Belgium, in Brussels, Wallonia and Flanders. Call us to hear when a technician can reach your home.
BrusselsWalloon BrabantFlemish BrabantHainautNamurLiègeLuxembourg provinceAntwerpEast FlandersWest FlandersLimburg
The brands we work with
Our technicians work on all brands: they install, service and repair appliances from the major manufacturers. For a new installation, we recommend the model that suits your home and budget.
We buy our equipment from all the major Belgian wholesalers and suppliers, including Facq, Van Marcke and Desco: genuine parts, quickly available.
Frequently asked questions
What does fault 04 mean on a Wolf boiler?
No flame was formed when the burner tried to start. Gas supply, ignition and ionisation electrodes and the gas valve are the usual causes.
What is the difference between 04 and 05?
04 occurs at start-up, when the burner fails to light. 05 occurs while the boiler is running, when the flame goes out.
My Wolf shows 01: is it dangerous?
The boiler has protected itself against overheating and will stay off. The cause, often poor water circulation or a pump problem, must be found by a technician.
Fault 12, 14 or 15: what are they?
They concern temperature sensors: flow, hot water and outdoor. The sensor or its cable is tested and replaced if necessary.
What should I do when a fault number appears?
Note the number and call us. Restarting the boiler several times does not remove the cause.
Can you get Wolf spare parts?
Yes, through Belgian suppliers. The engineer tells you when the part will be available and gives the price beforehand.
Your Wolf shows a fault number?
Call us or book online: a heating engineer comes to find the cause and repair your boiler.