Main PCB Junkers Cerapur Compact ZWB 24-1/28-1 (Heatronic 3 Z 10003) Ref. 8 737 702 723
Main PCB Heatronic 3 (Z 10003) for Junkers Cerapur Compact ZWB/ZSB -1. It manages ignition, pump, fan, gas valve, and sensors. Useful when faults F0, A8, AC, b1, or EA appear and after ruling out sensors/wiring. Refurbished part with reference 8 737 702 723.
VAT included
Consult via WhatsAppJunkers boilers compatible with reference 8 737 702 723
PCB with reference 8 737 702 723. Two confirmed compatibilities: ZWB 24-1 DE 23 and ZWB 28-1 DE 23.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Junkers ZWB 24-1 DE 23 | Cerapur Compact | Contrasted |
| Junkers ZWB 28-1 DE 23 | Cerapur Compact | 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 the reference 8 737 702 723 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.
Symptoms and faults that the PCB 8 737 702 723 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
F0 recurring or random
Cause: Internal fault of the Heatronic 3 PCB
Cut power, check connectors and bus; if F0 reappears with peripherals OK, replace the PCB.
- 02
b1 when turning on after maintenance
Cause: Incorrectly connected encoder or faulty reading on PCB.
Re-seat/measuring the encoder; if OK, the encoder input on the PCB may be damaged.
- 03
A8/AC with connected modules/controllers
Cause: Fault in Heatronic communication channel (PCB)
Test with another cable/bus; if the module works in another boiler, replace the PCB.
- 04
EA lock with spark and correct gas
Cause: Ignition/ionization stage on degraded PCB
Check electrodes and ground; if correct and without a recognized flame, check the PCB.
- 05
E9 despite being bled and with the pump operational
Cause: Erratic reading of NTC or thermal control on PCB
Measure NTC and continuity; check 24/5 V fuses on the PCB; if okay, replace the PCB.
Fault codes from Junkers that this part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| F0 | Internal electronics fault | Check the plugs and bus module; if the issue persists, replace the PCB/module according to the manual. Directly related to the main board. |
| A8 | Communication interrupted (bus) | Check the wiring between the bus module and Heatronic; if the bus and peripherals are correct, there may be a fault in the PCB. |
| AC | Module not detected | Check the connection between the module and the Heatronic; if the module is OK, suspect the communication channel on the PCB. |
| b1 | Encoder connector not detected | Set/measure the encoder connector that identifies the model; if correct and still b1, likely fault in the PCB. |
| EA | Flame not detected (ignition lock) | Check gas, pressure, electrodes, and wiring; if spark/ionization are correct, check ignition stage/flame reading on the PCB. |
| E2 | Faulty outgoing NTC | Measure the NTC and its cable; if the values are correct, the analog input on the PCB may be damaged. |
| E9 | Overtemperature trip on supply | Bleed the system and check the pump; check the 24 V fuse on the PCB. If the hydraulics are correct, check the PCB. |
| F7/FA | Flame detected with burner off / false flame after closing gas | Dry/check electrodes and siphon; if false signal persists, check ionization circuit on 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 PCB 8 737 702 723
- Catalogue reference
- 8 737 702 723
- Brand
- Junkers
- Type of part
- PCBs (control boards)
- Units in stock
- 1 unit
- 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.
- Control platform
- Bosch Heatronic 3 (screen printing Z 10003)
- Reference on PCB
- 8 737 702 723 (8737702723)
- Equivalents/substitutes
- 8737707762; 8748300488 (supply/kit); 87377074270; 86389001340
- Fuses in electronics
- T 2.5 A AC 230 V; T 1.6 A DC 24 V; T 0.5 A DC 5 V (on PCB)
- Verified compatibility
- Cerapur Compact ZWB 24-1 DE 23; ZWB 28-1 DE 23 (ZSB/ZWB -1)
- Managed functions
- Ignition, flame detection, fan, pump, gas valve, NTC readings, and bus.
- Absolute cut-off of power and gas before intervening; verification of absence of voltage.
- Electrostatic discharge (ESD): handle the PCB with an anti-static wrist strap/mat.
- Bleeding the circuit after the replacement to avoid E9 due to air and overheating.
- Replace gaskets and single-use cable glands if associated elements are disassembled.
- Check and replace fuses with the same type/value; investigate the cause of the trip.
- Parameterization: check/adjust service functions of Heatronic 3 after replacement.
- Wiring and connectors: do not force; respect the guidelines and codifications of the original harness.
Frequently asked questions about the PCB 8 737 702 723
Is this PCB compatible with my Junkers Cerapur Compact boiler?
My boiler shows the fault code EA, could it be the PCB?
What reference should I look for if I need to replace my PCB?
How many models are compatible with this PCB?
Do I need to reprogram anything after changing the PCB?
I have seen other references like 87377074270, are they equivalent?
