Pressure switch XP600 - Ariston Microtec T2 LLS 23 MFFI boiler
The XP600 pressure switch from Ariston is a device that checks the pressure in the boiler, allowing its operation according to the established parameters. When it fails, it can cause the boiler not to start or to lock out, even if the pressure is correct, which can lead to fault code E02: insufficient water pressure in the circuit. This model is compatible with various Ariston boilers, such as Microtec 23 MFFI, Microgenus 21 MFFI, and Microsystem 21, among others. It is recommended to replace the pressure switch when faults in the boiler startup or unexpected lockouts are detected.
VAT included
Consult via WhatsAppAriston boilers compatible with reference 995903
Pressure switch with reference 995903. 17 verified compatibilities: Microtec 23 MI and Microtec 23 MFFI / T2 LLS 23 MFFI.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Ariston Microtec 23 MI | Ariston | Contrasted |
| Ariston Microtec 23 MFFI / T2 LLS 23 MFFI | Ariston | Contrasted |
| Ariston Microgenus 21 MFFI | Ariston | Contrasted |
| Ariston Microgenus 28 MFFI | Ariston | Contrasted |
| Ariston Microgenus 31 MFFI | Ariston | Contrasted |
| Ariston Microgenus Plus 24 MFFI | Ariston | Contrasted |
| Ariston Microgenus Plus 28 MFFI | Ariston | Contrasted |
| Ariston Microgenus Plus 31 MFFI | Ariston | Contrasted |
| Ariston Microgenus II 24 | Ariston | Contrasted |
| Ariston Microgenus II 28 | Ariston | Contrasted |
| Ariston Microsystem 15 | Ariston | Contrasted |
| Ariston Microsystem 21 | Ariston | Contrasted |
| Ariston Microsystem 28 | Ariston | Contrasted |
| Ariston Selecta 24 MFFI | Ariston | Contrasted |
| Ariston Modula 23 | Ariston | Contrasted |
| Ariston Talia Green HP | Chaffoteaux | Contrasted |
| Ariston Talia Green System HP | Chaffoteaux | 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. 995903 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 995903. 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 pressure switch 995903 resolves.
The pressure switch controls the air or water pressure to authorize operation. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The boiler does not ignite and a pressure warning appears on the display, although the pressure gauge shows normal pressure.
Cause: The pressure switch does not close the contact even though the pressure is correct, because the internal mechanism is jammed or the contact is oxidized.
Measure the actual pressure on the boiler's manometer: if it is at a normal value and the fault persists, the problem is with the pressure switch, not with the pressure.
- 02
The boiler stops by itself in the middle of a heating cycle, without the water level dropping or the pressure changing.
Cause: The pressure switch intermittently switches due to an internal fault and cuts off the supply even though the pressure is within range.
Note if the cut coincides with vibrations, water hammer, or the pump starting; if the pressure gauge does not move during the cut, suspect the pressure switch.
- 03
The boiler starts and operates normally even if the circuit has low pressure, without any warning.
Cause: The pressure switch contact is stuck closed and does not break the circuit when the pressure falls below the minimum safety level.
With the boiler running, bleed air and observe if the pressure gradually decreases without any warning; if so, the pressure switch is not cutting off.
- 04
After filling and bleeding the circuit, the boiler still won't start and shows the same pressure fault.
Cause: The pressure switch may have a damaged contact mechanism, so it does not react even though the pressure is correct.
Check that there is no trapped air in the circuit and that the pressure remains stable for a while before considering the replacement of the pressure switch.
Fault codes for Ariston that this part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| E02 | Insufficient water pressure in the circuit (safety shutdown). | If the minimum water pressure switch remains open or is miscalibrated, the PCB interprets insufficient pressure and triggers E02; check the switch continuity with >1 bar and inspect the tube/capillary connections for obstruction. |
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.
Datasheet for Ariston pressure switch 995903
- Catalogue reference
- 995903
- Brand
- Ariston
- Type of part
- Pressure switches
- Units in stock
- 5 units
- 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.
- Model (label code)
- XP600
- Electrical contacts
- 10(2)A / 250V~
- Pressure range
- 0.2 - 1.2 bar
- Thermal marking (bulb)
- T125 μ
Frequently asked questions about the pressure switch 995903
Does this pressure switch XP600 work for the Ariston Microtec T2 LLS 23 MFFI?
At what pressure does this pressure switch operate in an Ariston Microgenus?
Is this pressure switch compatible with the Ariston Desy 24?
What electrical capacity do their contacts support?
Spare parts related to Ariston Ariston
