The Nuova Simonelli Aurelia II puts a specific message on the display when a monitored function does not behave as expected. Some messages are reminders. Others are protective shutdowns. A few let the machine continue making drinks while quietly losing temperature data, meter data, or control reliability.
Do not treat an alarm as a generic “reset the machine” instruction. Record the message exactly, including the group number and any CC or NC suffix. Write down what the machine was doing, whether the alarm cleared, and how often it returned. A single probe connection event is different from the same message on every cycle.
The full Aurelia II display-message list
The names below are the complete set covered by this guide. The response depends on whether the message is a maintenance reminder, a group-specific production fault, a boiler safety fault, or a control-board communication problem.
MAINTENANCE ALARM
This is a service reminder. The Aurelia II tracks elapsed time or shot count and displays the alarm when the interval set in the menu is reached. Use Menu > Maintenance to review the date or cycle setting and reset the reminder after the required work. It does not normally stop service, but leaving it for weeks defeats the purpose of the counter. Record what maintenance was actually done instead of only clearing the message.
BATTERY ALARM
On Digit and T3 versions, the electronic control unit uses a CR2032 coin cell for the clock and meter data while the machine is off. The alarm means the cell should be replaced. It usually will not stop a shift immediately, but a power loss before replacement can erase date, time, or meter information. The electronics enclosure must be opened for the cell swap, so it is best handled during a scheduled service rather than by repeatedly dismissing the message.
GROUP DOSE ERROR
The flowmeter on that group stopped sending pulses within 3 seconds after a pour began. The flowmeter may be failing, or its wiring may not be delivering the signal to the control system. The machine cannot measure the dose correctly on that group. Stop using the affected group, use another group only if it has no related fault, and preserve the group number for the technician. Continuing to pull shots can produce inconsistent or completely wrong volumes.
GROUP POUR ERROR
A delivery ran longer than 240 seconds without stopping, so the safety timer intervened. Possible causes include a stuck or failed flowmeter, a solenoid that did not close, or a control-board input problem. Do not keep using that group until it is diagnosed. An open solenoid running water for four minutes can flood the work area and may damage the machine.
PRESSURE ERROR
The boiler pressure switch detected pressure above 1.60 bar. The heating element shuts off automatically as a protective response. If pressure falls and the machine recovers once, record the event and watch for a repeat. If the message returns, the pressure switch or heating element becomes suspect. A repeated PRESSURE ERROR that does not clear is a shut-down-now situation. Do not bypass the protection or keep running a boiler at unsafe pressure.
LEVEL ERROR
The auto-level sequence timed out. With the pump running, the Aurelia II expects the boiler to fill within 90 seconds. Without the pump, the limit is 180 seconds. If the machine cannot reach the correct level in that window, it stops the pump and heating element and displays the alarm.
Likely causes include a failed level probe, a water-supply problem, or a weak pump. Check the external water supply only if that is part of normal operator procedure. Do not keep restarting the machine to force a fill. A technician checks inlet pressure, probe continuity, pump output, and the control response.
BOILER PRESSURE SWITCH ERROR
This is not the same as PRESSURE ERROR. PRESSURE ERROR means the sensed pressure went above 1.60 bar. BOILER PRESSURE SWITCH ERROR means the pressure-switch sensor circuit itself has a fault. The display may show CC for a short circuit or NC for not connected or open circuit.
With this alarm the machine may not be able to read boiler pressure correctly, which means it may not be able to protect itself correctly. Treat it as a call-a-tech-today condition even if the machine still appears to heat.
GROUP PROBE X ERROR / BOILER PROBE X ERROR
These messages identify a temperature sensor on group X or boiler X. The display also reports CC or NC. CC means a short circuit, such as probe wires touching where they should not. NC means the probe is disconnected or has failed open.
The affected group or boiler is effectively flying blind on temperature. Shots may be inconsistent and can be badly under-extracted if the group runs cold. Stop using the affected group. A technician checks the connector at the probe first, traces the cable to the control board, and then tests or replaces the probe if the wiring is sound.
CC STEAM PROBE 1 / 2 ERROR
The steam-wand temperature sensor has a short circuit. The machine falls back to timed steam mode rather than temperature-controlled steam. Milk texturing can become inconsistent even when steam still comes out. It is not the same urgency as a pressure safety alarm, but the probe should be replaced during service rather than allowing unreliable steam control to continue.
CUP WARMER PROBE 1 / 2 ERROR
The cup-warmer temperature sensor has failed. CC indicates a short circuit and NC indicates a disconnected or open sensor. The warmer may run without accurate temperature control. This is usually lower urgency than a group, boiler, or pressure alarm, but it belongs on the service list.
EEPROM WRITE ALARM / RTC READ ERROR / RTC WRITE ERROR
These are control-board memory and clock messages. An EEPROM write alarm means the board could not save settings or meter data. An RTC READ ERROR or RTC WRITE ERROR means the real-time clock has a read or write failure. The machine may still pull shots while losing settings, dates, or meter information.
One power cycle can show whether a one-time event clears. If any of these messages persist, the control board needs evaluation. Do not order a board only because the message exists. The technician confirms the history, connectors, power, and whether the error returns after the machine is stable.
SERIAL COMS ERROR
The control board and display are not communicating cleanly. Causes include a loose ribbon cable, interference, or a failing board. A single event after a power disturbance can be recorded and checked with one restart. If the message returns, the cabling and board need inspection. Do not continue clearing it indefinitely because a clean display does not prove that the two control sections are communicating reliably.
ERROR: NON-COMPATIBLE CONTROL UNIT
This means the installed control board does not match what the rest of the machine expects. It most often appears after the wrong board version is installed or after a firmware mismatch. It is not a bar-side reset. The machine needs the correct control-unit identification and a technician who can verify the board and firmware relationship.
What the alarm family tells a technician
When I see a probe alarm, I begin at the probe connector and follow the cable back to the control board. Many GROUP PROBE NC messages are a connector that vibrated loose rather than a failed sensor. For LEVEL ERROR, I check water pressure at the inlet, level-probe continuity, and pump output. For repeated PRESSURE ERROR, I test the pressure switch and inspect the heating element.
The stored error history matters. Tell the technician which alarm appeared, which group number was named, and roughly how often it fired. That pattern distinguishes an intermittent connector from a component that is failing every cycle.
What staff can do safely
Reset a MAINTENANCE ALARM through the maintenance menu after the scheduled work. A single power cycle can be used to see whether a one-time SERIAL COMS ERROR or LEVEL ERROR clears, provided the machine is otherwise safe. Check the external water supply if that is a normal staff task. Document the result.
That is about the limit. The BATTERY ALARM may look harmless because service continues, but changing the CR2032 requires access to the electronics enclosure. Do not bypass a pressure shutdown, continue using a group with PROBE or DOSE errors, or keep restarting a machine with repeated level or pressure faults. The alarm exists because the control system detected a real condition.
For the commercial coffee machine repair service, bring the exact message, group number, CC or NC suffix, and the time pattern.
Urgency guide
Call promptly for LEVEL ERROR, BOILER PRESSURE SWITCH ERROR, or a PRESSURE ERROR that does not self-clear. Multiple-group GROUP PROBE errors and any alarm that returns after a restart deserve the same attention. A single CUP WARMER PROBE 1 / 2 ERROR or BATTERY ALARM can usually wait for a scheduled visit if the rest of the machine is operating safely.
For a busy cafe, a full preventive service once a year is a minimum baseline. That visit should include probe inspection, solenoid cleaning, level-probe checks, and replacement of wear parts before they create alarms in the middle of service. Clearing the message is only the beginning. The machine must be safe, measured, and reliable again.