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Wolf error codes
The most common codes for Wolf gas boilers (CGB and others), with what they mean and what to do.
The code appears on the Wolf controller, sometimes with « FC » in front: FC4 and 4 are the same code.
Overheating or water pressure too low (under 1 bar): the boiler has shut down.
PressureCheck the pressure gauge. If it's too low, top up the water (if you know how) and bleed the radiators. If the pressure drops again, there's probably a leak: call us.
No flame when the burner starts.
IgnitionCheck that the gas tap is open, then reset the boiler once. If the code comes back, don't keep trying: repeated resets can lock the appliance. Call us.
The flame went out just after ignition.
IgnitionCheck that the gas tap is open, then reset the boiler once. If the code comes back, don't keep trying: repeated resets can lock the appliance. Call us.
The heating water is too hot: check the pressure, bleeding or pump.
CirculationCheck the pressure and that the radiator valves are open. If everything looks fine and the code comes back, the water circulation needs checking (pump, bleeding, sensors): call us.
The return is hotter than the flow: check bleeding, pressure or pump.
CirculationCheck the pressure and that the radiator valves are open. If everything looks fine and the code comes back, the water circulation needs checking (pump, bleeding, sensors): call us.
Flue gases too hot, or the flue or air supply is blocked.
Flue · safetySwitch the boiler off and air the room. This code concerns the flue: call us. If a CO alarm goes off, or anyone has a headache or nausea, get everyone outside and call 112.
Unstable flame signal: blocked condensate trap or flue, or a severe storm.
Flue · safetySwitch the boiler off and air the room. This code concerns the flue: call us. If a CO alarm goes off, or anyone has a headache or nausea, get everyone outside and call 112.
The flame signal drops out: electrode or gas quality.
TechnicianA component or electronics fault: this needs a technician. Don't open the boiler; call us and give the code shown.
A flame is detected before the burner starts.
TechnicianA component or electronics fault: this needs a technician. Don't open the boiler; call us and give the code shown.
A flame is still detected after shutdown: gas valve fault.
TechnicianA component or electronics fault: this needs a technician. Don't open the boiler; call us and give the code shown.
The fan doesn't reach its start-up speed.
TechnicianA component or electronics fault: this needs a technician. Don't open the boiler; call us and give the code shown.
Faulty flow sensor, or gas pressure too low.
TechnicianA component or electronics fault: this needs a technician. Don't open the boiler; call us and give the code shown.
The hot water sensor or its cable is faulty.
TechnicianA component or electronics fault: this needs a technician. Don't open the boiler; call us and give the code shown.
This code isn't in the list: call us and give it to us, we'll tell you straight away what's going on.
Source: Wolf, CGB gas condensing boiler installation and operating instructions (3062555, wolf.eu). Codes and how they're shown can differ between models: if in doubt, your appliance's manual applies.
First steps
- Write down the code shown: it saves us time.
- Check the pressure gauge.
- Check that the gas tap is open.
- Reset once. If the code comes back, call us.
Practical guides: Top up the pressure · Bleed a radiator · Reset the boiler
A breakdown, a question? Get in touch.
Call us or message us on WhatsApp. Or leave your number, with a photo of the boiler if you like: we'll call you back.
