Nuova Simonelli Aurelia II Message DIAGNOSIS OF ERROR: Memory Chip
DIAGNOSIS OF ERROR appears on a Nuova Simonelli Aurelia II (Digit, V and S) when the control unit finds a problem with its own memory chip during its start-up diagnosis. The machine will not heat and every function is blocked. Turn it off at the main switch, try once more and call us if the message appears again.
High: all machine functions are blocked until the control is repaired.
- Code
- DIAGNOSIS OF ERROR
- Maker
- Nuova Simonelli
- Equipment
- Espresso machines
- Applies to
- Aurelia II Digit / V / S
What does Nuova Simonelli error code DIAGNOSIS OF ERROR mean?
Each time an Aurelia II is switched on, its control unit runs a start-up diagnosis before it allows anything to work. One of the checks tests the memory chip (EPROM) that holds the machine's program. If that check finds a problem, the display shows DIAGNOSIS OF ERROR. The machine will not heat and every function is blocked, because a control with a damaged program cannot be trusted to run a boiler. This is a control board problem, not something a barista can clear with a setting or a cleaning step. The possible causes are the memory chip itself, the control board and its connections, the power supply to the board, or an interrupted program change, where the machine lost power while its settings were being written. A single power-off and on is reasonable because a momentary supply glitch during start-up can produce the message. If it appears again, nothing the operator can do at the front of the machine will help, and opening the cabinet only adds risk.
Affected models and control systems
This applies to Nuova Simonelli Aurelia II machines in the Digit, V and S versions (User Handbook, March 2012).
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
- DIAGNOSIS OF ERROR on the display at start-up
- No heating and no water delivery
- Keys not responding
- The same message after every restart
Possible causes
Listed in Nuova Simonelli's documentation
- Control unit memory chip (EPROM) failed
- Control board or its connections damaged
- Power supply to the board unstable
- Machine lost power during a program change
Other likely causes — what usually sits behind error code DIAGNOSIS OF ERROR on this control. A technician confirms which one it is before any part is replaced.
- Voltage spike from the building supply damaging the memory
- Control board contacts corroded by steam and moisture
- Board connector loosened by years of vibration
Safe checks before calling for service
- Turn the machine off at the main switch until the display goes dark.
- Turn it on again and watch for the message.
- If it appears again, keep the machine off and leave the panels shut.
- Call us to schedule service and tell us the model, such as Aurelia II Digit.
How a technician diagnoses error code DIAGNOSIS OF ERROR
- Read the message and confirm it repeats at each start-up.
- Check the supply voltage and grounding at the machine.
- Inspect the control board and its connectors for moisture or damage.
- Check the memory chip and its seating.
- Replace the memory or board and set up the machine's settings.
- The control board is wired to live line voltage and sits near the hot boiler.
- Replacing the memory means loading the machine's own settings.
- Opening the cabinet around steam and hot parts risks burns.
How error code DIAGNOSIS OF ERROR differs from similar codes
Boiler over 130 C and the grinding messages are operating messages. DIAGNOSIS OF ERROR blocks the machine before it starts.
Technical reference
- Document
- Aurelia II (S, V, Digit) User Handbook March 2012, Function Messages p.75-78
- Edition
- March 2012 (Marzo 2012); no part number printed
- Models / control
- Aurelia II Digit / V / S
- Section
- 10. Aurelia Digit Machine Function Messages, p. 75-76 (messages listed as DIAGNOSIS OF ERROR, DELIVERY ERROR, DOSER ERROR, LEVEL ERROR, PRESSURE ERROR, OVERCURRENT ERR., FINE GRINDING, COARSE GRINDING); 11. Aurelia V, p. 77; 12. Aurelia S, p. 78
- 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 Nuova Simonelli espresso machine error codes
Can I clear DIAGNOSIS OF ERROR with a key?
No. It comes from the control's own start-up check, and the machine stays blocked.
Will turning it off and on help?
Once, yes. If the message returns, the memory or board needs service.
Could a power cut have caused it?
Yes, especially if the machine lost power while its program was being changed.
Need help with Nuova Simonelli error code DIAGNOSIS OF ERROR?
A technician confirms the cause on site and gives you the price in writing before any work starts.