Junkers Heatronic 3 PCB · 8748300923 for Cerapur Comfort ZWBC 30-2 C 23
It is the main control board: it manages ignition, fan, pump, modulation, and safety features. It is suspected in case of internal faults (F0), data errors (b2), or communication errors (A8), after verifying sensors, wiring, and the coded connector.
- Type of part
- Junkers
- Status
- Refurbished
- Catalogue reference
- 8748300923
- Warranty
- 1 year
Junkers boilers compatible with reference 8748300923
Junkers with reference 8748300923. Five confirmed compatibilities: Junkers Cerapur Comfort ZWBC 30-2 C 23 and Junkers Cerapur Comfort ZWBC 25-2 C 23. There are three other models that we are still verifying.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Junkers Cerapur Comfort ZWBC 30-2 C 23 | Junkers | Contrasted |
| Junkers Cerapur Comfort ZWBC 25-2 C 23 | Junkers | Contrasted |
| Junkers Cerapur Comfort ZWBC 25-2 C 31 | Junkers | Contrasted |
| Junkers Cerapur Comfort ZWBC 30-2 C 31 | Junkers | Contrasted |
| Junkers Cerapur Comfort ZWBC25-2C 23S3700 | Junkers | Contrasted |
Models pending verification
These models are associated with this reference, but we have not finished verifying them yet, so we do not consider them compatibleIf your boiler is one of them, send us a photo of the part you are going to replace and we will verify it before you purchase.
| Junkers Cerapur ZWBC 24-2 C 23, 24-2 C 31 and 28-2 C 23 | Junkers | Unconfirmed |
|---|---|---|
| Junkers Cerapur ZWBC 28-2 C 31 | Junkers | Unconfirmed |
| Junkers Cerapur Comfort ZWBC25-2C 31S3700 | Junkers | Unconfirmed |
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
The part reference, model, and equipment revision must be verified against the manufacturer's documentation.
- Check the label on your boiler for the exact model (for example, ZWBC 30-2 C 23) and compare it with the list of compatible boilers.
- With the boiler powered off, open the front panel: the PCB is located behind it, in the control box. The 8748300923 is usually printed on the printed circuit board or on a sticker on the side.
- Compare the number and position of relays and connectors with the photos: under the same reference, there are different versions.
- If they match, call us at 911 17 77 77 with your boiler model and we will reserve it for you.
Symptoms that require diagnosis in the junkers 8748300923
Common symptoms and faults
- 01
The boiler does not ignite or respond to the commands from the front panel.
Cause: To confirm: it attributes it to the PCB. First, check the fuses: the manual indicates three on the board.
- 02
Erratic fault codes on the screen without apparent reason.
Cause: To confirm: it attributes it to the PCB. Check the sensors, wiring, and coded connector first.
- 03
Fault code F0 (internal fault).
Cause: The official manual instructs to check the ignition contacts and cables, and if necessary, replace the PCB.
- 04
The display shows F0 (internal fault).
Cause: Faulty electrical contacts or ignition cables, or internal fault of the PCB.
Check the electrical contacts, the ignition cables, and the gas/air ratio. Replace the PCB only if necessary.
- 05
The display shows the fault code b2.
Cause: Fault code of the boiler's PCB.
Check the coded connector, the sensors, and the wiring first. If the fault persists, the PCB is the suspect.
- 06
The display shows A8 (communication interrupted with the BUS).
Cause: Communication with the BUS has been interrupted. If the BUS checks do not explain it, the cause may be in the PCB.
Check the BUS wiring and its connections, as well as the coded connector, before replacing the PCB.
- 07
The display shows F7: the boiler detects a flame while being off.
Cause: Electrodes in poor condition, issue in the flue or moisture on the PCB.
Check the electrodes, the flue, and ensure that the PCB is not damp.
Junkers fault codes that require diagnosis
| Code | Fault | Technical checks |
|---|---|---|
| F0 | Internal fault | Check the electrical contacts and the ignition cables, as well as the gas/air ratio. If necessary, replace the PCB. |
| b2 | Fault code of the PCB | Check the coded connector, the sensors, and the wiring. If the fault persists, consult a technician: the cause may be in the PCB. |
| A8 | Communication interrupted with the BUS | Check the BUS wiring and the coded connector before replacing the PCB. |
| F7 | Flame detected with the appliance off | Check the electrodes and the flue, and ensure that the PCB is not wet. |
| E9 | Temperature limiter triggered | Check the service pressure, the temperature limiter, the operation of the pump, and the fuses on the PCB, and bleed the boiler. |
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.
Technical sheet: Junkers 8748300923
- Catalogue reference
- 8748300923
- Uniclima internal SKU
- PECZWBC30X
- Brand
- Junkers
- Type of part
- Junkers
- Units in stock
- 1 unit
- 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.
- Type of part
- Main PCB / control module
- Control system
- Heatronic 3
- Component manufacturer
- Omron
- Nominal coil voltage of the relay
- 24 VDC
- Declared functions
- Ignition, fan, pump, modulation, and safety features
- Relay model mounted
- OMRON G5RL-1A-E-HR
- Relay contacts
- 16 A, 250 VAC
- Source of additional data
- Declared information; auxiliary references and applications without equivalent from the accredited manufacturer.
- Inventory — Application indicated in inventory
- Compatible with reference: Main PCB Heatronic 3 for the Junkers Cerapur Comfort ZWBC 30-2 C 23. It controls ignition, fan, pump, modulation, and safety features. This refurbished unit replaces the original when there are internal faults (F0), data errors (b2), or communication issues (A8), after verifying sensors, wiring, and the coded connector.
- Inventory — Subcomponent
- OMRON G5NB-1A-E relays; 24 VDC coil.
- Manufacturer information — Fuses
- 3 on the PCB; spare parts behind the cover · Official manual 6 720 615 759
- Pending applications to verify
- Junkers Cerapur Comfort ZWBC 30-2 C 23 — mentioned in the current description; pending documentary verification.
- The b3 in the official manual is a fault of the differential pressure switch; another website lists it as an error of the electronics data. Follow the manual.
- In E9, the manual instructs to check the pressure, limiter, pump, and fuses of the PCB.
- To confirm: Junkers Cerapur ZWBC 24-2 C 23, 24-2 C 31 and 28-2 C 23 — by model: (same); only by family ZWBC24/ZWBC28.
- To confirm: Junkers Cerapur ZWBC 28-2 C 31 — by model:;, only by family ZWBC28
- To confirm: Junkers Cerapur Comfort ZWBC25-2C 31S3700:
- Do not confuse: 7 716 010 270 — Number that some provide along with the model ZWBC 30-2 C 23 (referred to as "Serial Number") — explains what it identifies; the reference of the PCB is 8748300923.
- The 8748300714 and the version identifiers come from a single one each, without explanation: compare your PCB before ordering.
- (same in: same catalog, 1 origin) and they join the 8748300923 to the ZWBC 30-2 C 23. It is registered as new and as original; they have it refurbished and that is what matters.
Frequently asked questions: junkers 8748300923
How do I identify the Junkers Heatronic 3 8748300923 PCB?
Is it compatible with my Junkers Cerapur Comfort ZWBC 30-2 C 23?
Is it compatible with other Cerapur Comfort models, such as the ZWBC 25-2 C or the 30-2 C 31?
What do 8748300923, Heatronic 3, and 7 716 010 270 mean?
Are there different versions with the same reference?
What fault does this PCB indicate?
Can I install it myself?
How to identify this PCB?
