PCB Junkers Bosch Ceraclass Excellence ZWC 35 35 3 MFA Ref. 8748300931
The Junkers Bosch Ceraclass Excellence ZWC 35 35 3 MFA 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 exhibit erratic behavior, showing symptoms such as fault code F0: Internal fault or F7: Despite being off, a flame is observed in the unit. This PCB is compatible with boilers from the Junkers ZWC range, such as models ZWC 24/28, ZWC 30/30, and ZWC 35/35, among others. It should be replaced when the mentioned symptoms are detected.
VAT included
Consult via WhatsAppJunkers boilers compatible with reference 8748300931
PCB with reference 8748300931. Three confirmed compatibilities: ZWC 24/28 and ZWC 30/30.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Junkers ZWC 24/28 | Junkers ZWC (Euromaxx) | Contrasted |
| Junkers ZWC 30/30 | Junkers ZWC (Euromaxx) | Contrasted |
| Junkers ZWC 35/35 | Junkers ZWC (Euromaxx) | 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. 8748300931 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 8748300931. 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 8748300931 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 is completely off, it doesn't respond to anything.
Cause: The PCB does not distribute power to the other components of the boiler.
Check the network terminal block (L, N, LR, Ls, Ns) for voltage before replacing the PCB.
- 02
A fault code appears on the screen and the boiler locks out without further action.
Cause: The electronics detect an anomaly and cut the cycle for safety.
Note the fault code and rule out the implicated sensor before blaming the PCB.
- 03
The boiler control is not responding, even though it has power.
Cause: The PCB does not process communication with the remote control or the external programmer.
Check the wiring and connectors between the control and the PCB before replacing it.
- 04
The boiler keeps turning on and off by itself repeatedly.
Cause: An intermittent fault in the control circuit randomly interrupts the power supply.
Check if the cut coincides with the use of domestic hot water or heating, it helps to narrow down the source.
Fault codes from Junkers that this part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| F0 | Internal fault. | The PCB (printed circuit board) has an internal hardware/data fault that blocks management; the manufacturer advises replacing the PCB if, after checking power supply and connectors, the error persists. Verify by measuring voltages, checking connectors and fuses on the PCB, and, if necessary, testing with a replacement board. |
| F7 | Despite being turned off, a flame is visible on the appliance. | Moisture/leakage on the PCB causes a false ionisation signal and the electronics interpret a non-existent flame. Verify by inspecting and drying the PCB, checking the ionisation circuit and ruling out condensates/leaks; if it persists, check the ionisation input on the PCB or replace it. |
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 8748300931 PCB.
- Catalogue reference
- 8748300931
- Brand
- Junkers
- Type of part
- PCBs (control boards)
- Units in stock
- 1 unit
- 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 ZWC 35/35 Manual (PDF)Document © Junkers, provided as a technical reference.
Frequently asked questions about the PCB 8748300931
Is this PCB suitable for a ZWC 30/30 boiler?
Is the label LR, Ls, Ns, N, L seen in the photo the code of the PCB?
Spare parts related to Junkers Junkers ZWC (Euromaxx)
