PCB Junkers Cerastar/Euroline ZR-ZSR-ZWR-ZWE Ref. 8748300281
The Junkers Cerastar/Euroline ZR-ZSR-ZWR-ZWE PCB is the component responsible for controlling the ignition, burner modulation, pump, and safety features of the boiler. When this part fails, the boiler may not start, become locked, or behave erratically, potentially displaying the fault code E9: STB activated. It is compatible with models such as ZR 18-3, ZR 24-3, ZSR 18-3, ZSR 24-3, ZWR 18-3, and ZWR 24-3, among others. A technician must confirm through diagnosis whether it needs to be replaced when the aforementioned symptoms occur to restore its operation.
- Type of part
- PCBs (control boards)
- Status
- Refurbished
- Catalogue reference
- 8748300281
- Warranty
- 1 year
Junkers boilers compatible with reference 8748300281
PCB with reference 8748300281. Seven confirmed compatibilities: ZR 18-3 and ZR 24-3.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Junkers ZR 18-3 | Junkers Cerastar (ZR/ZSR/ZWR -3) | Contrasted |
| Junkers ZR 24-3 | Junkers Cerastar (ZR/ZSR/ZWR -3) | Contrasted |
| Junkers ZSR 18-3 | Junkers Cerastar (ZR/ZSR/ZWR -3) | Contrasted |
| Junkers ZSR 24-3 | Junkers Cerastar (ZR/ZSR/ZWR -3) | Contrasted |
| Junkers ZWR 18-3 | Junkers Cerastar (ZR/ZSR/ZWR -3) | Contrasted |
| Junkers ZWR 24-3 | Junkers Cerastar (ZR/ZSR/ZWR -3) | Contrasted |
| Junkers ZR 11-3 | Junkers Cerastar (ZR/ZSR/ZWR -3) | 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. 8748300281 is the part for your boiler
The part reference, model, and equipment revision must be verified against the manufacturer's documentation.
- Find the reference printed on the installed part and check whether it matches the catalogue reference 8748300281. 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 that require diagnosis on the PCB 8748300281
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 light up any indicators or respond to the control panel.
Cause: The PCB does not distribute power to the control circuits.
Measure with a multimeter if 230V is reaching the terminal block of the PCB and check the fuses T0.5A and T1.6A before replacing it.
- 02
One of the fuses blows again shortly after replacing it.
Cause: It usually indicates a short circuit in the PCB itself, not a faulty fuse.
Before replacing the fuse, disconnect the external components (pump, fan) one by one and check if it holds; if not, the fault is in the PCB.
- 03
The boiler ignites but shuts off after a few seconds with a lockout.
Cause: The PCB does not properly process the flame or sensor signal and cuts off the gas supply for safety.
Check that the connectors for the sensors and the electrode are properly seated in the terminal block before replacing the PCB.
- 04
The fault code on the display does not match any obvious fault in the other components.
Cause: It may be due to an incorrect reading by the microcontroller on the PCB due to internal damage.
Reset the boiler and note if the same code always reappears consistently; if it's erratic, it points more towards the PCB than an external component.
Junkers fault codes that require diagnosis
| Code | Fault | Technical checks |
|---|---|---|
| E9 | STB activated | When you see "E9" on the display, it means that the STB (safety device) has been activated. If the PCB is not operational, it may not properly manage the signal from the NTC or the safety system. Check the NTC input, the operation of the pump, and the fuse on the printed circuit board. |
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 8748300281 PCB.
- Catalogue reference
- 8748300281
- Uniclima internal SKU
- PECZWR243
- Brand
- Junkers
- Type of part
- PCBs (control boards)
- Units in stock
- 0 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- Delivery time shown at checkout
- Return
- 14 days
Part data and available documentation
Contrast the label codes, PCB, and revision with the installed part; they are not necessarily equivalent references.
- Power supply (terminal block)
- 24 V
- Fuse 1
- T0.5A
- Fuse 2
- T1.6A
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Junkers ZSR 24-3 Manual (PDF) Document © Junkers, provided as a technical reference.
Frequently asked questions about the PCB 8748300281
Is this PCB suitable for the Junkers ZSR18-3?
What electrical data can be seen on the PCB of the Junkers Cerastar/Euroline?
How many models are compatible with this PCB?
What fault code is documented for this PCB?
What is the reference for this PCB?
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