Randell E02

What does Randell E02 mean?

On a Randell prep table with the Danfoss controller, E02 is the S2 Sensor Failure alarm. S2 is one of the controller's temperature sensors (thermistors). E02 indicates the controller cannot read a valid value from S2 because the sensor has failed, drifted out of range, or lost its connection, affecting the function that sensor controls.

Symptoms

• Display shows E02 with the alarm LED lit
• Temperature control tied to the S2 sensor is affected
• Displayed temperature may be missing or incorrect
• Defrost or cooling behavior may be abnormal

Common causes

• Failed or out-of-range S2 thermistor
• Disconnected or loose S2 sensor connector at the controller
• Damaged sensor wiring
• Controller input fault

Diagnostic steps

1. 01

   Confirm the alarm

   Verify the Danfoss display reads E02, the S2 Sensor Failure alarm.

2. 02

   Disconnect power before inspecting

   Ensure the unit is disconnected from its power source before checking the sensor or wiring, per the manual.

3. 03

   Inspect the S2 sensor connection

   Check that the S2 thermistor is connected at the controller and that its wiring is not damaged or loose.

4. 04

   Verify cabinet temperature

   Compare the displayed temperature against the set point to judge whether the unit is still holding safe temperature.

5. 05

   Contact service

   The Danfoss table directs contacting service for a sensor failure; call 888-994-7636 to test or replace the S2 thermistor.

When to call a professional

The Danfoss code table directs contacting service for an S2 sensor failure. Identifying which thermistor is at fault and replacing it with the correct OEM part is service-technician work, and the manual requires factory-authorized service with OEM parts on these R290 units. Call a Randell Authorized Service Agent at 888-994-7636 if E02 does not clear after checking the connection.