Danfoss E17

What does Danfoss E17 mean?

E17 is the cut-out (open-circuit) message for the S3 sensor on a Danfoss EKC controller. The S3 input has lost continuity, so the controller cannot read that temperature. On superheat controllers S3 is part of the superheat calculation, so a missing S3 disturbs regulation. The alarm relay activates at high priority and the front-panel LEDs flash.

Symptoms

• Display shows E17 when the alarm is recalled.
• S3 temperature reading is missing or out of range.
• Front-panel LEDs flash to indicate the regulation error.
• Superheat regulation becomes unreliable while S3 is absent.

Common causes

• S3 sensor cable is broken or open-circuit.
• Loose or corroded terminal at the S3 connection.
• Failed S3 temperature sensor.
• Sensor reading outside its valid measuring range.

Diagnostic steps

1. 01

   Recall and clear the alarm

   Press the top button to show E17 on the display, then press again to cancel the active alarm.

2. 02

   Inspect the S3 wiring

   Power down and check the S3 cable and terminals for breaks, looseness, or corrosion; re-seat any suspect connection.

3. 03

   Measure the S3 sensor

   Disconnect S3 and measure its resistance; an open reading confirms a broken sensor or cable.

4. 04

   Replace the S3 sensor

   Fit a new sensor of the specified type, keep its cable clear of power wiring, and confirm E17 clears on power-up.

When to call a professional

Because S3 feeds the superheat calculation, leaving E17 unresolved can affect compressor protection. If you cannot find the open circuit or the sensor is in an awkward suction-line position, call a refrigeration technician. They will replace the S3 sensor, confirm the controller reads it correctly, and re-verify superheat regulation. Working in an energised control panel is not advisable for untrained staff.