Junkers CerapurComfort ZWBC 25-2 C PCB (control board)
The Junkers CerapurComfort ZWBC 25-2 C PCB 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, and it may display the fault code F0: Internal error. This board is compatible with models from the Cerapur Comfort range ZWBC, such as the ZWBC 24-2C, ZWBC 25-2C, ZWBC 28-2C, and ZWBC 30-2C, among others. It is recommended to replace it when these symptoms or faults occur.
VAT included
Consult via WhatsAppBosch Junkers 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 |
|---|---|---|
| Bosch Junkers ZWBC 24-2C | Cerapur Comfort ZWBC (2C) | Contrasted |
| Bosch Junkers ZWBC 25-2C | Cerapur Comfort ZWBC (2C) | Contrasted |
| Bosch Junkers ZWBC 28-2C | Cerapur Comfort ZWBC (2C) | Contrasted |
| Bosch 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 shows no signs: the display does not turn on, the fan does not start, nothing happens when pressing the button.
Cause: The PCB distributes the 230V power to the other components; if it fails, the entire system loses power.
Measure with a multimeter that there is voltage at the input connector of the PCB and that the fuse on the PCB itself is not blown.
- 02
The display shows a fault code that doesn't go away no matter how much you reset the boiler.
Cause: The microprocessor on the PCB locks the unit when it detects an internal fault or a fault in a connected component.
Note the exact code and check it before purchasing: many codes point to the sensor, the pressure switch, or the gas valve, not to the PCB.
- 03
The boiler starts, makes an attempt, and stops on its own, repeating the cycle several times in a row.
Cause: One of the relays on these PCBs may not close the contact properly, causing erratic starts and stops.
Listen for a clear click from the relay when starting; if the click is irregular or not heard, check the PCB before looking at other parts.
- 04
The wall control is unresponsive, as if the boiler and the control are not communicating with each other.
Cause: The PCB manages the communication with the control; if that circuit fails on the PCB, the control becomes unresponsive even if it is functioning properly.
Disconnect and reconnect the remote control cable directly on the PCB: a loose connector gives the same symptom as a faulty board.
Fault codes for Bosch Junkers that this part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| F0 | Internal error. | The PCB (control board) has an internal fault (e.g., A/D converter, memory, or power supply), triggering the "F0". Check voltages and wiring, encoder connections, and if the error persists after reset and testing, replace the PCB 8748300923. |
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 Bosch Junkers PCB 8748300923
- Catalogue reference
- 8748300923
- Brand
- Bosch Junkers
- Type of part
- PCBs (control boards)
- Units in stock
- 2 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- 1-2 business days
- Return
- 14 days
Data read on the part and in the manufacturer's documentation
What we have not been able to verify does not appear here.
- Manufacturer of the mounted relays
- Omron (G3RL-1A-E-HR, 24V DC)
Frequently asked questions about the PCB 8748300923
Does this PCB work for the Junkers Cerapur ZWBC 24-2 C?
Do the Omron G3RL-1A-E-HR relays mounted on this PCB confirm that they are from the Omron factory?
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