Junkers Eurostar ACU HIT PCB Ref. 8748300344
If your boiler does not start, locks out, or behaves erratically, you may need the Junkers Eurostar ACU HIT PCB. This control board manages the ignition, burner modulation, pump, and safety features of the boiler. When it fails, you may see the fault code F0, which indicates an internal fault or a fault with the printed circuit board. It is compatible with models from the ZWSE23 and ZWSE28 ranges, among others. It should be replaced when it shows faults that affect the proper performance of the boiler.
VAT included
Consult via WhatsAppJunkers boilers compatible with reference 8748300344
PCB with reference 8748300344. Two confirmed compatibilities: ZWSE23 and ZWSE28.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Junkers ZWSE23 | ZWSE23 | Contrasted |
| Junkers ZWSE28 | ZWSE28 | 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. 8748300344 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 8748300344. 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 8748300344 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
An error code appears that does not correspond to any actual fault with the sensor, pressure switch, or gas valve.
Cause: The PCB interprets the signals from all the sensors of the boiler; if it fails, it generates codes that point to components that are actually functioning properly.
Note the exact code and measure the indicated component before assuming it is the PCB.
- 02
The thermostat or room control does not control the boiler, although it works fine on its own.
Cause: The communication between the control and the boiler goes through the PCB; if it fails, control is lost without the control being at fault.
Check the connectors and wiring of the bus between the control and the PCB before replacing the PCB.
- 03
The display or indicators are acting strangely: flickering, intermittent blackouts, or nonsensical symbols.
Cause: A fault in the internal power supply of the PCB or in its microcontroller is usually noticed on the display before a total boiler lockout.
Cut the power for a few seconds and check if the fault reappears immediately; if it returns quickly, it points to the PCB.
- 04
Every time there is a power outage, the boiler starts as if it were the first time: no time, no programming, no saved settings.
Cause: This data is stored in a memory on the PCB with auxiliary power; if that part fails, everything recorded is lost with each power cut.
Check if this PCB has a backup battery and what condition it is in before assuming the entire board is faulty.
Fault codes from Junkers that this part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| F0 | Internal fault / PCB fault. | Defect in the PCB (Heatronic/PCB) causing internal control fault; check power supply and connections/plugs, and if the wiring and BUS module are correct but the F0 persists, 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 8748300344 PCB.
- Catalogue reference
- 8748300344
- Brand
- Junkers
- Type of part
- PCBs (control boards)
- Units in stock
- 5 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 ZWSE23 manual (PDF)Document © Junkers, provided as a technical reference.
Frequently asked questions about the PCB 8748300344
Is this PCB compatible with my Junkers ZWSE23 boiler?
Spare parts related to Junkers ZWSE23
