Manitowoc E31 Error Code

What does Manitowoc E31 mean?

E31 is a safe mode notification, not a shutdown fault. When the ice thickness probe (ITP) or water level probe fails, certain Manitowoc Indigo models activate safe mode, allowing the machine to continue producing ice for up to 72 hours using default timing parameters rather than sensor-based control. E31 alerts the operator that a sensor has failed and the machine is running on a fixed-time backup cycle. If not repaired within 72 hours, the machine transitions to standby and halts production.

Symptoms

• E31 is displayed or logged while the machine continues to make ice.
• Ice slab thickness may be inconsistent — too thin or too thick — without ITP feedback.
• A concurrent E19 (ITP fault) is typically present in the event log.
• Machine transitions to standby and stops production if E31 is not resolved within 72 hours.

Common causes

• Ice thickness probe (ITP) failure triggering safe mode fallback.
• Water level probe fault triggering safe mode on applicable models.
• ITP disconnected, scaled, or mechanically damaged.

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Diagnostic steps

1. Identify the triggering sensor fault

   Review the event log for concurrent codes alongside E31 — typically E19 (ITP fault) or an E25/E26/E27 (bin probe fault). The co-existing code identifies the failed sensor driving safe mode.

2. Clean the ice thickness probe immediately

   Run a clean-and-sanitize cycle using Manitowoc-approved cleaner. Soak the ITP for 10 minutes in Manitowoc cleaning solution. A scaled ITP is the most common trigger for E31 safe mode.

3. Inspect ITP connection and adjustment

   Confirm the ITP connector is firmly seated at the control board and the probe gap to the evaporator matches the specification in the service manual. Reconnect or readjust as needed.

4. Replace the ITP if cleaning does not resolve E19

   If the ITP frequency reading in diagnostics remains outside range after cleaning and adjustment, replace the probe with the Manitowoc-specified part. Safe mode will exit automatically once a valid sensor reading is restored.

5. Monitor ice slab quality during safe mode operation

   While in safe mode, inspect each ice slab manually to confirm acceptable thickness. Default timing may not produce optimal ice under all ambient and water temperature conditions.

When to call a professional

If the sensor causing safe mode cannot be identified or replaced within the 72-hour window, call a licensed service technician immediately to prevent a full production shutdown. Continued operation in safe mode is a temporary workaround, not a permanent fix.