La Marzocco Espresso Machine Error Code: Coffee Boiler 1 Overheated
Coffee Boiler 1 Overheated means the coffee boiler temperature exceeded the maximum allowed. The manual says to call a service technician, and the CPU also turns power off to the coffee boiler.
High: the boiler exceeded its maximum temperature, a safety condition.
- Code
- Coffee Boiler 1 Overheated
- Maker
- La Marzocco
- Equipment
- Espresso machines
- Applies to
- Linea PB and Strada AV
What does La Marzocco Coffee Boiler 1 Overheated mean?
The CPU compares the coffee boiler temperature with a maximum limit. If the boiler goes past that, the CPU cuts power to the coffee boiler and shows Coffee Boiler 1 Overheated. The manual says to call a service technician. A boiler can overheat if the heater stays switched on when it should be off, if the probe reads low so the control keeps heating, or if the boiler is running short of water. It is the high-temperature counterpart of the not heating message. Because overheated brew water and a hot, pressurized vessel are dangerous, the CPU takes the heater out of service rather than waiting. On a working espresso machine the coffee boiler sits close to the groups, so the first thing the barista notices is water that comes out far hotter than usual, or a machine that goes quiet when the heater is cut. Shots pulled from an overheated boiler taste burnt, which is another reason the machine should not be used until it has been checked.
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
- Coffee Boiler 1 Overheated on the display
- Coffee boiler heater cut off
- Group head very hot
- Steam or hissing from the machine
Possible causes
Likely causes — what usually sits behind Coffee Boiler 1 Overheated on this control. A technician confirms which one it is before any part is replaced.
- Heater relay stuck closed
- Coffee boiler probe reading lower than actual
- Boiler short of water
- Heater control output not switching off
Safe checks before calling for service
- Switch the machine off and keep clear of the boiler.
- Let it cool completely.
- Do not restart repeatedly.
- Check for leaks or steam, without opening panels.
- Note the display and anything you saw.
How a technician diagnoses Coffee Boiler 1 Overheated
- Read the message and the boiler number.
- With power locked out, check the heater relay for welded contacts.
- Compare the probe reading with a reference thermometer.
- Verify the boiler water level and look for leaks.
- Replace the failed part, then confirm control.
- An overheated boiler holds scalding water under pressure.
- A welded relay is a line-voltage problem.
- A meter and reference thermometer are needed.
How Coffee Boiler 1 Overheated differs from similar codes
This is the over-temperature message for the coffee boiler. The steam boiler has its own matching message.
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 it dangerous?
The boiler may hold very hot water, so keep clear until it cools.
Can I reset it?
The manual says to call a technician.
Can the probe be the cause?
It can be, since a probe reading lower than the real temperature lets the heater run on.
Need help with La Marzocco Coffee Boiler 1 Overheated?
A technician confirms the cause on site and gives you the price in writing before any work starts.