PCB Junkers Bosch Cerapurcomfort Zwbc 25 2C Ref. 8748300923
The Junkers Bosch Cerapurcomfort ZWBC 25 2C PCB (control board) Ref. 8748300923 is the component that controls the ignition, burner modulation, pump, and safety features of the boiler. When it fails, the boiler may not start, lock out, or operate erratically, displaying the fault code E9: STB activated. This board is compatible with the models ZWBC 24-2C, ZWBC 25-2C, ZWBC 28-2C, and ZWBC 30-2C from the Cerapur Comfort range. It should be replaced when these symptoms or operational faults occur.
VAT included
Consult via WhatsAppJunkers boilers compatible with reference 8748300923
PCB with reference 8748300923. Four confirmed compatibilities: ZWBC 24-2C and ZWBC 25-2C.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Junkers ZWBC 24-2C | Cerapur Comfort ZWBC (2C) | Contrasted |
| Junkers ZWBC 25-2C | Cerapur Comfort ZWBC (2C) | Contrasted |
| Junkers ZWBC 28-2C | Cerapur Comfort ZWBC (2C) | Contrasted |
| Junkers ZWBC 30-2C | Cerapur Comfort ZWBC (2C) | Contrasted |
Can't see your model or have questions? The printed reference takes precedence. How to check it · Send us a photo via WhatsApp.
How to check if ref. 8748300923 is the part for your boiler
What determines it is not the boiler model, but the reference printed on the part you already have installed.
- Find the reference printed on the installed part and check whether it matches the catalogue reference 8748300923. If it is not visible, do not identify the part from its shape alone.
- Check the full boiler model on its data plate and look for it in the model associations on this page.
- Compare the connections and physical body with the original part before installation.
- If anything is unclear, send us a photo of the marking via WhatsApp before placing your order.
Symptoms and faults that the PCB 8748300923 resolves
The PCB controls the ignition, modulation, and safety features of the boiler. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The boiler does not ignite, there are no indicators or active display.
Cause: A fault in the power supply to the PCB leaves the entire control electronics without power.
Check the general power supply of the boiler (plug, differential, fuse) before replacing the PCB.
- 02
The display shows a fault code that does not match any visible fault.
Cause: The control circuit of the PCB can fail intermittently and generate alerts without any real external cause.
Note the exact fault code and reset the boiler to see if the error recurs before changing the PCB.
- 03
The thermostat or the control does not manage to control the boiler, as if they were not communicating.
Cause: The communication stage of the PCB may have failed, rendering the commands from the control ineffective.
Check the wiring and the connection of the control in the terminal block of the PCB before replacing it.
- 04
The boiler turns on and off repeatedly without any apparent reason.
Cause: A relay on the PCB that does not close or cut off properly can cause erratic starts and stops of the burner.
Listen to see if the clicks of the relays coincide with the unexpected on and off before blaming the PCB.
Fault codes from Junkers that this part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| E9 | STB activated | When you see "E9" on the display, it means that the STB has been activated. This can occur if the PCB is not functioning properly and is not adequately controlling the system. Check the NTC input, the operation of the pump, and the fuse of the printed circuit. |
These symptoms can have more than one cause. If your boiler displays a fault code, send it to us via WhatsApp along with a photo of the labeling, and we'll tell you if this is the part.
Data sheet for the Junkers 8748300923 PCB.
- Catalogue reference
- 8748300923
- Brand
- Junkers
- Type of part
- PCBs (control boards)
- Units in stock
- 15 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- Delivery time shown at checkout
- Return
- 14 days
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Junkers ZWBC 30-2C manual (PDF)Document © Junkers, provided as a technical reference.
Frequently asked questions about the PCB 8748300923
Does this PCB work for any ZWBC 24-2, 25-2, 28-2, or 30-2 C boiler?
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