Junkers (Bosch) PCB HT II-2a · 8 748 300 488 for ZWA 24-1 AM 23

Application for the exact variant pending confirmation. Control board for the functions of the boiler. The relationship with the PCB 8 748 300 561 0 of group 06, control panel of the ZWA 24-1 AM, requires verification before replacing it.

Type of part: PCBs (control boards)
Status: Refurbished
internal SKU: PLC219
Warranty: 1 year

VAT included Stock · 6 units

Compatibility

Junkers (Bosch) boilers compatible

PCB. 0 verified compatibilities. There are another 9 models that we are still checking.

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 ZWA 24-1 AM 31	Junkers (Bosch)	Unconfirmed
Junkers ZWA 24-1 KM 31	Junkers (Bosch)	Unconfirmed
Junkers ZWA 24-1 KM 23	Junkers (Bosch)	Unconfirmed
Junkers ZWA 24-1 A 24	Junkers (Bosch)	Unconfirmed
Junkers (Bosch) Junkers ZWA 24-1 (AB, AI), 24-1/3 (AB, AI), 28-1 (AB, AI, AM) and 28-1/3 (AB, AI)	Junkers (Bosch)	Unconfirmed
Junkers ZWA 24-1/3 AM	Junkers (Bosch)	Unconfirmed
Junkers (Bosch) Buderus Logamax U022-24 and U022-28 (KB, KI, also V3S)	Junkers (Bosch)	Unconfirmed
Junkers (Bosch) Worcester 24Si and 28Si Mk 2 (Si II)	Junkers (Bosch)	Unconfirmed
Junkers (Bosch) Junkers ZWA 24-1 AM 23	Junkers (Bosch)	Unconfirmed

Can't see your model or have questions? The printed reference takes precedence. How to check it · Send us a photo via WhatsApp.

Guide

How to check if it is the part for your boiler

The part reference, model, and equipment revision must be verified against the manufacturer's documentation.

Look for the code 8 748 300 488 (8748300488) and the designation HT II-2a CA CA CA on the label.
Check the fuses: T1.25A next to the glass fuse and T2A next to the ceramic fuse.
your PCB has 8748300561 or 8 748 300 561 0, it can be a substitute for 488: like "ex 8748300488" and as an equivalent, but they list it separately. It is not confirmed: compare before ordering.
Do not confuse it with the coding connector 8 714 421 161 0 or with the codes 8 748 300 496 (list of the ZWA 24-1 A) and 8 748 300 431 0 (list of the K).
if they match, call us at 911 17 77 77 with the model of your boiler.

Diagnosis and fault codes

Symptoms that require diagnosis on the PCB

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 heating is not working, but domestic hot water is coming out.
Cause: Incorrect signal from the room thermostat, or faulty room thermostat, or fault in the PCB.
Check the room thermostat and its wiring. If the heating still does not work, have a technician check it.
02
The boiler is not working and the indicators are not lighting up, even though there is a demand for heating.
Cause: There is no voltage reaching the device: fuse F1 or F2, transformer, electrical connection, or PCB.
Check that the boiler has power and that the switch is turned on. If it does not turn on, have a technician check 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.

Technical data

Technical sheet: Junkers (Bosch) PCB

Uniclima internal SKU: PLC219
Brand: Junkers (Bosch)
Type of part: PCBs (control boards)
Units in stock: 6 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.

Marked next to fuse holder: T1.25 A
Inventory — Marked next to the ceramic fuse: T2A
Inventory — Application indicated in inventory: Junkers ZWA 24-1 AM 23
Identification — Marked designation: HT II-2a CA CA CA
Identification — Marked code: HT II-2a CA CA CA
Identification — Marked code: 8 748 300 488
Marked next to fuse holder: T1.25 A
Inventory data — Marked next to the ceramic fuse: T2A
Inventory data — Application indicated in inventory: Junkers ZWA 24-1 AM 23
Pending applications to verify: Junkers ZWA 24-1 AM 23 — compatibility noted; pending confirmation by variant.

Before purchasing

To confirm: Junkers ZWA 24-1 AM 31 — e; and / they only give the AM family, without suffix.
To confirm: Junkers ZWA 24-1 KM 31 — e; and / they only give the KM family, without suffix.
To confirm: Junkers ZWA 24-1 KM 23; and / they only provide the KM family.
To confirm: Junkers ZWA 24-1 A 24 — gives 488; the list for the ZWA 24-1 A gives 496: discrepancy.
To confirm: Junkers ZWA 24-1 (AB, AI), 24-1/3 (AB, AI), 28-1 (AB, AI, AM) and 28-1/3 (AB, AI) — (8748300488) and that they give 8748300561 as "ex 8748300488" (—without the 28-1 AB, this one with 87483005610); by family.
To confirm: Junkers ZWA 24-1/3 AM — (8748300561 ex 8748300488) and a copy of its list (8 748 300 561 0)
To confirm: Buderus Logamax U022-24 and U022-28 (KB, KI, also V3S) — (8748300488) and (87483005610 ex 8748300488)
To confirm: Worcester 24Si and 28Si Mk 2 (Si II)
Do not confuse: 8 714 421 161 0 — Coding connector (spina di codifica) of the control panel group of the ZWA 24-1 AM, according to a spare parts list (group 06) — Another part: it is not the PCB.
Do not confuse: 8 748 300 496 — PCB of the ZWA 24-1 A (another variant) — It is not the one for the AM 23.
Do not confuse: 8 748 300 431 0 — PCB of the ZWA 24-1 K (another variant) — It is not the one for the AM 23.
To confirm: and / they list 8748300561 in another product and British writes it backwards ("8748300488 Was 8748300561").
Level 3 for the code identity 488 (/); the suffix 23 is only given. Discrepancies: and / list separately the 8748300561 "ex 488"; gives the 488 for the A 24, which the A list does not confirm.
Pending registered applications to confirm by model, variant, or programming: Junkers ZWA 24-1 AM 23.

Frequently Asked Questions

Frequently asked questions about the PCB (control board)

Where is the code for this PCB and what other markings should I compare?

It is marked on the PCB: 8 748 300 488, next to the designation HT II-2a CA CA CA. Also compare the fuses (T1.25A and T2A). without spaces: 8748300488.

Is it compatible with my Junkers ZWA 24-1 AM 23?

The compatibility of this variant is pending confirmation. Registered: for the ZWA 24-1 AM 23. They also provide it for that model with the 8748300488, and / for the ZWA 24-1 AM. If your boiler is another model, call 911 17 77 77 or send us a photo via Contact.

Is it compatible with the ZWA 24-1 AM 31 or the KM?

The compatibility of this variant is pending confirmation. Registered application: the ZWA 24-1 AM 31 and the KM 31, and also for the KM 23. It is only provided for the ZWA 24-1 AM/KM family, without suffix. Only the AM 23 has been registered: compare your code or call us at 911 17 77 77.

What is the difference between 8748300488 and 8748300561?

and (it is given as 87483005610) and Italian ones sell the 8748300561 as "ex 8748300488" (previous code); write "8748300488 = 8748300561". An Italian copy, without author, of the ZWA 24-1 AM list includes the 8 748 300 561 0, without the 488. and / they list them as different products and British ones reverse them. Compare your code.

Is it compatible with a ZWA 24-1 A or K, or with other Eurosmart?

The compatibility of this variant is pending confirmation. The spare parts list for the ZWA 24-1 A provides 8 748 300 496 and for the K it gives 8 748 300 431 0 (copies, for reference). It gives 488 for the A 24: compare your code. Those lists are not for the KM: check the question for the AM 31 or the KM. For the ZWA 24-1 AB/AI, the 24-1/3, and the 28-1, it provides 488 and 8748300561 (ex 488): to be confirmed.

What do 8 748 300 488, HT II-2a CA CA CA, and 8 714 421 161 0 mean?

8 748 300 488 is the code marked on the plate and the one they use. HT II-2a CA CA CA is the designation marked on the plate; note on the relay or mounted subcomponent "HT 11-2a" and "CA CA CA". The 8 714 421 161 0 is not the plate: it is a coding connector (group 06 of an Italian copy, without author, of a spare parts list).

Who should install it?

A qualified technician: the PCB controls a gas boiler and is connected to the electrical network. Any questions? Send us a photo of the PCB and the boiler's rating plate from Contact.

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Junkers (Bosch) PCB HT II-2a · 8 748 300 488 for ZWA 24-1 AM 23