Saunier Duval Isomax C 28 E2 Control Module Ref. 05721000
The Saunier Duval Isomax C 28 E2 Control Module is a PCB that manages the ignition, burner modulation, pump, and safety features of the boiler. When it malfunctions, the boiler may fail to start, become locked, or operate erratically, displaying fault codes such as F12, F18, or F13. This module is compatible with several boilers from the Isofast and Isomax ranges, including the C 28 E model. A technician must confirm through diagnosis whether replacement is necessary when these symptoms or operational errors are detected.
Saunier Duval boilers compatible with reference 05721000
PCB with reference 05721000. 14 verified compatibilities: C 28 E and C 28 E1.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval C 28 E | Isofast | Contrasted |
| Saunier Duval C 28 E1 | Isofast | Contrasted |
| Saunier Duval C 28 E NOx | Isofast | Contrasted |
| Saunier Duval C 28 E1 NOx | Isofast | Contrasted |
| Saunier Duval C 35 E | Isofast | Contrasted |
| Saunier Duval C 35 E1 | Isofast | Contrasted |
| Saunier Duval F 28 E | Isofast | Contrasted |
| Saunier Duval F 28 E1 | Isofast | Contrasted |
| Saunier Duval F 35 E | Isofast | Contrasted |
| Saunier Duval F 35 E1 | Isofast | Contrasted |
| Saunier Duval C 28 E | Isomax | Contrasted |
| Saunier Duval C 28 E2 | Isomax | Contrasted |
| Saunier Duval F 28 E | Isomax | Contrasted |
| Saunier Duval F 28 E2 | Isomax | 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. 05721000 is the part for your boiler
The part reference, model, and equipment revision must be verified against the manufacturer's documentation.
- Find the reference printed on the installed part and check whether it matches the catalogue reference 05721000. 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 that require diagnosis on the PCB 05721000
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 shows no signs of life: no lights, no display, and no noise when trying to start.
Cause: The PCB controls the power supply and the start of the boiler; if it fails, nothing starts.
First, check the fuse on the PCB, the main circuit breaker of the house, and verify that power is reaching the input connector.
- 02
The control or the display lights up, but when pressing the start button, nothing happens; the boiler does not attempt to start.
Cause: The microcontroller receives the command, but does not activate the ignition sequence (fan, igniter, gas valve).
Cut the power for one minute and try again; also check that the flat cable of this module is properly connected at both ends.
- 03
The boiler works for a while and then shuts off by itself, without giving any fixed fault code.
Cause: An intermittent fault on the PCB (cold solder joint or component that overheats) causes interruptions that do not always repeat the same error.
Note if the cut always coincides with the start of the pump or the fan: if so, suspect those components more than the PCB.
- 04
It skips a different fault code each time, or one that does not appear in the boiler manual.
Cause: When the control electronics are damaged, it misinterprets the signals from the sensors and generates erratic fault codes.
Note the exact code and compare it with the manual before discarding the PCB: it may indicate a sensor or a probe, not the module itself.
Fault codes Saunier Duval that require diagnosis
| Code | Fault | Technical checks |
|---|---|---|
| F12 | No signal from the user interface | Yes — it points to this display/interface module or its connection cable with the main PCB. |
| F18 | User interface fault | Yes — it corresponds to this display/control board module. |
| F13 | Main PCB fault | No — that code is for the MAIN PCB (a different part), not for this display. |
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 Saunier Duval 05721000 PCB.
- Catalogue reference
- 05721000
- Uniclima internal SKU
- MMIC28E2
- Brand
- Saunier Duval
- 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.
- Saunier Duval F 28 E Manual (PDF)Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the PCB 05721000
Is this module compatible with the Saunier Duval Isomax C 28 E2?
Does this Isofast/Isomax electronic module come with the connection cable?
Is this module compatible with the Saunier Duval Isofast F 28 E1?
Spare parts related to Saunier Duval Isofast
