Junkers Bosch Cerapur Comfort ZWBC Heatronic 3 PCB Ref. 8748300923
The Junkers Bosch Cerapur Comfort ZWBC Heatronic 3 PCB, with reference 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, become locked, or exhibit erratic operation, potentially displaying the fault code F0: Internal error. This PCB is compatible with models such as the ZWBC 24-2C, ZWBC 25-2C, ZWBC 28-2C, and ZWBC 30-2C, among others in the Cerapur Comfort range. It is recommended to replace it upon noticing these symptoms or if the mentioned error occurs.
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 display is flashing or showing a fixed fault code, and the boiler does not attempt to ignite.
Cause: The Heatronic on the PCB blocks the start-up when it detects a safety condition that does not match.
Turn off the boiler for one or two minutes and then restore power; if the fault code reappears without you having touched anything, it is an indication of a PCB fault.
- 02
The boiler does not attempt to ignite: there is no sound from the fan or ignition spark.
Cause: The PCB does not send the signal to start the fan and ignition; if it does not emit that signal, the boiler remains idle.
Check that the thermostat is actually calling for heat by setting it above the ambient temperature before assuming it is the PCB.
- 03
The boiler loses its programming or settings and reverts to factory values by itself.
Cause: The memory that stores the configuration is on the PCB; if it fails, the unit forgets the adjusted parameters.
Reprogram the values and check if they are lost again after a power cut or a reset, to distinguish a one-time fault from one related to the PCB.
- 04
There is a burnt smell or dark marks can be seen at some point on the PCB.
Cause: A power component, such as the relay mounted on this PCB, can overheat and leave a visible mark before completely failing.
With the boiler unplugged, inspect the PCB with a flashlight looking for brown or black stains around the relays or the transformer.
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
- 10 pcs
- 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.
- Relay code mounted on the PCB
- 8 737 702 723
- Relay batch code
- Z 10003
- Week/year of manufacture of the relay
- G 12/13
Frequently asked questions about the PCB 8748300923
Is this Heatronic 3 PCB compatible with the Junkers Bosch ZWBC 28-2 C31?
What code does the relay mounted on the PCB of the ZWB 25-2 C23 have?
Spare parts related to Bosch Junkers Cerapur Comfort ZWBC (2C)
