La Marzocco Espresso Machine Error Code: Steam Boiler Probe Failed
Steam Boiler Probe Failed means the CPU does not detect the steam boiler temperature probe. The CPU shuts down and turns off the machine. The manual says to reset by verifying and reconnecting the temperature probe.
High: the CPU shuts the machine down because it cannot read the steam boiler temperature.
- Code
- Steam Boiler Probe Failed
- Maker
- La Marzocco
- Equipment
- Espresso machines
- Applies to
- Linea PB and Strada AV
What does La Marzocco Steam Boiler Probe Failed mean?
The steam boiler is held at a set temperature using a probe that the CPU reads constantly. If it no longer detects the probe, the CPU cannot regulate the boiler and shows Steam Boiler Probe Failed. The manual states that the CPU shuts down and turns off the machine, and that the reset is to verify and reconnect the temperature probe. In practice that means checking the connector and lead, then testing the probe. A steam boiler without a temperature reading can overheat, so the machine does not carry on. The steam boiler also has a fill system with its own message, and this message is only about the probe, which is a different part. Steam performance depends on how well the boiler holds its set point, so a steam boiler without its probe cannot be trusted to make dry steam, and the control prefers to stop. The shutdown also protects the heater, because without a reading it could keep heating a boiler until it overheats.
Affected models and control systems
La Marzocco Linea PB (display software, Operating Manual V3.2) and Strada AV (MAN.16.1.01 V1.0). Boiler names and numbers on the display follow the machine's group and boiler count.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- Steam Boiler Probe Failed on the display
- Machine shuts down
- No steam available
- Message returns after switching on
Possible causes
Likely causes — what usually sits behind Steam Boiler Probe Failed on this control. A technician confirms which one it is before any part is replaced.
- Steam boiler temperature probe disconnected
- Probe lead broken or damaged by heat
- Probe connector loose or corroded
- Probe input on the CPU not reading
Safe checks before calling for service
- Switch the machine off and let it cool.
- Do not open panels or touch the boiler.
- Switch on once to see whether the message returns.
- If it does, leave the machine off.
- Note the display and any recent movement or service.
How a technician diagnoses Steam Boiler Probe Failed
- Read the message and confirm the steam boiler.
- Inspect the probe connector and lead.
- Measure the probe resistance with power off and compare it with temperature.
- Reconnect and test the CPU input.
- Replace the probe or lead if it fails and verify steam control.
- The probe is in a hot pressurized boiler.
- The connector sits in the line-voltage area.
- A meter and reference temperature are needed.
How Steam Boiler Probe Failed differs from similar codes
This is the steam boiler probe. Coffee Boiler 1 Probe Failed is the same message for the coffee boiler.
Technical reference
- Maker documentation
- La Marzocco owner support
- Edition
- V3.2 - 12/2015 (La Marzocco S.r.l.)
- Models / control
- Linea PB and Strada AV
- Section
- Troubleshooting, printed pp. 104-105 (PDF pp. 104-105)
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related La Marzocco espresso machine error codes
Is the boiler broken?
Often just the probe or its connector.
Can I reset it?
The manual's reset is to verify and reconnect the probe.
Why does the whole machine shut down?
The CPU will not run a boiler it cannot measure.
Need help with La Marzocco Steam Boiler Probe Failed?
A technician confirms the cause on site and gives you the price in writing before any work starts.