Ako E1

What does Ako E1 mean?

The controller has detected a fault on Probe 1, the primary temperature control sensor. The fault is an open circuit, a crossed/short circuit, or a temperature reading outside the valid sensor range (NTC: above +110 °C or below -55 °C; PTC: above +150 °C or below -58 °C). When E1 is active, compressor behavior is governed by parameter C6 (stop, keep running, follow 24-hour average, or run on C7/C8 schedule).

Symptoms

• E1 alternates with the temperature display on the controller screen.
• Alarm relay and audible alarm activate.
• Compressor behavior changes according to C6 parameter setting.
• Temperature regulation from Probe 1 is suspended.
• Controller cannot protect product temperature without a functioning control probe.

Common causes

• Open circuit in the Probe 1 cable (most common).
• Short or crossed wiring at the probe terminal block.
• Probe installed in an area with extreme temperatures outside sensor limits.
• Moisture ingress or physical damage to the probe tip.
• Incorrect probe type for the installed controller configuration.

Diagnostic steps

1. 01

   De-energize the system and inspect Probe 1

   Switch off the controller. Examine the full probe cable run for physical damage, cuts, or pinch points. Check the probe tip for signs of corrosion or water ingress.

2. 02

   Check terminal block connections

   Verify Probe 1 is firmly connected at both the probe connector and controller terminal. Re-seat or re-terminate any loose connections.

3. 03

   Measure probe resistance

   Disconnect the probe and measure resistance at the tip with a multimeter. Compare against the AKO resistance–temperature curve for the probe type. An open-circuit or out-of-range reading confirms failure.

4. 04

   Review C6 parameter setting

   Until the probe is replaced, confirm C6 is set to an appropriate fallback mode to protect the stored product. C6=2 (run on 24-hour average) is generally safest for cold-room applications.

5. 05

   Replace the probe with AKO-approved replacement

   Install a new AKO-approved Probe 1. Route cable away from power wiring. Restore power and verify E1 clears and temperature regulation returns to normal.

When to call a professional

Call a licensed refrigeration technician if E1 occurs alongside high product temperatures, if the probe replacement does not clear the fault, or if internal controller diagnostics (such as C6 fallback behavior) are needed to protect product safety. Any compressor or refrigerant system investigation resulting from uncontrolled temperature during the fault also requires a qualified technician.