Identify the warning, do not guess the part.
If you Wolf CGB-2K show a code, copy the complete message and check the model. Here you will find the warnings from its manual and what information to provide for a review. A code guides: it does not confirm by itself which spare part is needed.
Models and version of the manual
20 and 24. Fault table from the CGB-2/CGB-2K manual. The warning numbers and fault codes are not interchangeable lists; check how it is presented by the installed control.
Consulted edition: 3063596_202001 · manufacturer's manualThe control options, accessories, and versions may limit which notifications appear in each installation.
Locate the code on your screen.
These accesses lead to their entry in the table. They are not a classification of the most common faults: the manual does not provide incidence statistics.
What to do without opening the boiler
- Note what you see.
Complete code, message, and pressure displayed by the equipment. Indicate whether it occurs when opening hot water, requesting heating, or in both cases.
- Identify the device.
Take a photo of the screen and the identification accessible without disassembling anything. Brand, model, and version help avoid confusing tables from different ranges.
- Describe how it started.
Determine whether the fault is continuous or intermittent and if there was a supply interruption or a recent intervention. If it reappears after a reset allowed by the user manual, do not chain resets.
Do not open the casing or manipulate gas, wiring, combustion, or flue gas outlet. If you smell gas, avoid flames and switches, leave the area, and notify the distributor's emergency service from a safe location; in case of immediate danger, call 112.
Documented codes table
The meaning of the warning is provided, not the repair operations reserved for qualified personnel. When the manufacturer groups several codes, the grouping is maintained; it is not interpreted as a range of numbers.
| Code | What does · source indicate? |
|---|---|
| 01 | Overtemperature STB ↗ |
| 02 | Overtemperature TB ↗ |
| 03 | dt-differential supply Differential eSTB ↗ |
| 04 | There is no flame. ↗ |
| 05 | The flame goes out. ↗ |
| 06 | Overtemperature TW ↗ |
| 07 | Combustion gas overtemperature TB ↗ |
| 08 | The combustion gas damper does not switch. ↗ |
| 255 | Unknown fault code ↗ |
| 10 | Faulty eSTB sensor ↗ |
| 11 | False call ↗ |
| 12 | Faulty boiler sensor ↗ |
| 13 | Faulty exhaust sensor ↗ |
| 14 | Faulty domestic hot water sensor ↗ |
| 15 | Faulty outdoor sensor ↗ |
| 16 | Faulty return sensor ↗ |
| 20 | VMG relay test (GKV) ↗ |
| 24 | Fan revolutions < ↗ |
| 26 | Fan revolutions > ↗ |
| 27 | Faulty domestic hot water sensor Faulty stratified accumulator sensor ↗ |
| 30 | CRC combustion control unit ↗ |
| 32 | 23 VAC power supply error ↗ |
| 35 | Missing BCC ↗ |
| 36 | Damaged BCC ↗ |
| 37 | Incorrect BCC ↗ |
| 38 | It is necessary to update the BCC. ↗ |
| 39 | BCC system error ↗ |
| 40 | Flow control (pressure increase check) ↗ |
| 41 | Flow control sensor (check sensor) ↗ |
| 52 | Maximum charging time of the accumulator ↗ |
| 53 | IO – Actual deviation ↗ |
| 54 | GLV actuators ↗ |
| 55 | GLV system fault ↗ |
| 56 | Factory limit calibration ↗ |
| 57 | Divergence calibration ↗ |
| 58 | Out-of-time calibration ↗ |
| 59 | Factory limit calibration ↗ |
| 78 | Common collector needle sensor (SAF) faulty ↗ |
| 90 | FA communication ↗ |
| 95 | Program mode. ↗ |
| 96 | Reset ↗ |
| 98 | Flame amplifier ↗ |
| 99 | Central combustion control system fault ↗ |
| 107 | CC pressure ↗ |
| 116 | External fault on parameterized input E1 ↗ |
Is there a problem, but no fault code appears?
The absence of a warning does not rule out a fault. For a boiler that does not heat, does not deliver hot water, loses pressure, or operates intermittently, describe the symptom and the moment it occurs. Do not assume that the PCB, the pump, or a sensor is faulty without checking the equipment and the installation.
Request a review of the boiler. · Consult maintenance
Before requesting a repair
Does the code identify the spare part I need to buy?
No. A single warning can have multiple causes. The spare part reference requires identifying the appliance and confirming the fault; the code or a generic photograph is not sufficient.
Can it be reset again if the fault returns?
It is not advisable to chain resets. Follow only what is outlined for the user in your version's manual. A persistent or recurring lockout requires inspection.
When does it make sense to compare a new boiler?
When you have a diagnosis and a budget, compare repair, availability of the spare part, and replacement according to your installation. An isolated fault code does not justify changing the equipment.
Models of this guide in the catalog
See new boilers · Consult installation or replacement
The technical sheet of each product provides information on its price and availability. Installation is quoted separately depending on the case.
Documentation and other guides
Official manual for Wolf CGB-2K · 3063596_202001. The page references in the table correspond to the PDF viewer, whose numbering may differ from the printed version.
Consult fault guides by brand and model. · Return to the blog