Eliwell E2

What does Eliwell E2 mean?

E2 indicates a fault on probe Pb2, the evaporator temperature probe. With Pb2 failed, the controller loses evaporator temperature feedback, so defrost cycles can no longer terminate on evaporator temperature and will run to their maximum time-out duration. The alarm icon remains on continuously while the fault persists.

Symptoms

• Display shows 'E2' continuously or alternating with room temperature.
• Alarm icon LED stays permanently on.
• Defrost terminates by time-out only, not by evaporator temperature.
• Minimum and maximum alarms are disabled.
• Buzzer activates if fitted.

Common causes

• Pb2 wiring is open-circuit due to broken cable or loose terminal.
• Pb2 probe is short-circuited.
• Probe type parameter H00 set to wrong NTC/PTC value for the fitted probe.
• Measured evaporator temperature is outside probe operating range.
• Pb2 connector corroded or disconnected from terminal block.

Diagnostic steps

1. 01

   Check Pb2 terminals and cable

   Power down the controller. Inspect Pb2 terminals and cable for corrosion, loose wires, or physical damage. Re-seat the connector and tighten terminal screws.

2. 02

   Verify probe type parameter H00

   Enter the programming menu and confirm H00 is set to match the fitted probe (0 = PTC, 1 = NTC). Cycle power after any change to apply the new setting.

3. 03

   Measure probe resistance

   Disconnect Pb2 and measure resistance with a multimeter. A good NTC probe reads ~10 kΩ at 25 °C; open or shorted reading confirms the probe has failed.

4. 04

   Replace Pb2 probe

   Install a new probe of the correct type and temperature rating. Route extension cable away from power wiring; NTC probes have no insertion polarity.

5. 05

   Confirm alarm clears and defrost logic restores

   Power up, verify E2 is gone, and manually trigger a defrost to confirm it terminates on evaporator temperature rather than time-out.

When to call a professional

If E2 persists after replacing Pb2 and correcting probe type settings, the controller's Pb2 input terminal or internal circuitry may be damaged. A qualified technician should perform electrical continuity testing on the wiring harness and inspect the controller board. Repeated time-out defrosts can cause ice accumulation on the evaporator, reducing system efficiency and risking product damage.