PCB Boiler ZWB28-3C23 Ref. 8748300941
The PCB for the ZWB28-3C23 Ref. 8748300941 boiler from Junkers controls the ignition, burner modulation, pump, and safety features of the boiler. When it fails, the boiler may not start, lock out, or behave erratically, which can lead to faults such as F0, EA, C6, or A7. This part is compatible with models like ZWB28-3C23, ZWB28-3C31, ZWB28-3CE23, among others from the Junkers Cerapur Smart range, as well as some from the Neckar NWB24-3C series. It is recommended to replace it when the mentioned symptoms occur or if the associated faults are detected.
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Consult via WhatsAppJunkers boilers compatible with reference 8748300941
PCB with reference 8748300941. Six confirmed compatibilities: ZWB28-3C23 and ZWB28-3C31.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Junkers ZWB28-3C23 | Junkers Cerapur Smart ZWB28-3C | Contrasted |
| Junkers ZWB28-3C31 | Junkers Cerapur Smart ZWB28-3C | Contrasted |
| Junkers ZWB28-3CE23 | Junkers Cerapur Smart ZWB28-3C | Contrasted |
| Junkers ZWB28-3CE31 | Junkers Cerapur Smart ZWB28-3C | Contrasted |
| Junkers NWB24-3C23 | Neckar NWB24-3C | Contrasted |
| Junkers NWB24-3CE23 | Neckar NWB24-3C | 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. 8748300941 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 8748300941. 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 8748300941 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 shows a fixed fault code that cannot be reset.
Cause: The PCB generates and maintains that code; if its electronics fail, the code persists even if there is no real problem.
Note the code and compare it with the fault list of your boiler; some codes indicate problems with the sensor or pressure, not with the PCB.
- 02
The boiler does not ignite at all, neither heating nor hot water, and the display is off or very dim.
Cause: If the PCB does not properly power the circuit, no component can be activated.
Check that power is reaching the boiler and verify that the fuse on the PCB is not blown.
- 03
The pump, the fan, or the gas valve activate by themselves, without a demand for heat.
Cause: The PCB controls the output relays; if any of them fail or get stuck, the component operates without a real command.
Disconnect that component and check if it continues to work: if it stops, the problem may be with it and not with the PCB.
- 04
The boiler starts up well but resets itself every few minutes.
Cause: An intermittent fault on the PCB can restart the control cycle without a real thermal reason.
Check that the connection box and the connectors on the PCB do not have any play or corrosion before replacing it.
Fault codes from Junkers that this part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| F0 | Incorrect reference voltage (internal electronics error). | The PCB (Heatronic/"control unit") may lose internal references or fail; check service parameters (8.d/8.C), wiring, and if it persists after resets and checks, replace the PCB. |
| EA | Flame not detected during ignition. | If gas, electrodes, and wiring are correct and the ionisation current is low/erratic, an electronic fault in the PCB (ignition/ionisation reading) may prevent flame detection; measure ionisation µA and, if after the diagnostic tree it persists, replace the PCB. |
| C6 | The fan does not start / fan fault/airflow. | After checking the connector, power supply, and fan, the manual indicates "electronic fault" and change of PCB; also in Bosch documentation, it is advised to check connections on the PCB and, if necessary, replace the 'control board'. |
| A7 | Defective DHW NTC sensor. | If the NTC and the harness ('baum') measure correctly even from the 20-pin connector, the reading circuit on the PCB itself may be faulty; measure the NTC at the sensor and on the PCB, and if there is an 'electronic fault', replace the PCB. |
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 8748300941 PCB.
- Catalogue reference
- 8748300941
- Brand
- 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.
- voltage
- AC 230V
- frequency
- 50Hz
Frequently asked questions about the PCB 8748300941
Is this PCB suitable for a ZWB28-3C23 boiler?
Is it also suitable for a ZSB14-3CE23?
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