Carel E406 Error Code

What does Carel E406 mean?

E406 on Carel humiFog controllers signals that the discharge pressure probe is faulty or disconnected. The discharge pressure probe monitors system outlet pressure for safety. Without a valid reading, the controller enters Disable mode, suspending humidification output while keeping the unit in a safe state. Manual reset is required after the probe fault is corrected.

Symptoms

• Humidifier output is disabled — steam or fog production stops.
• E406 (or E6 on older display formats) is shown on the controller.
• Discharge pressure reading is absent or out of range on the display.
• Manual reset is required to restore operation after repair.

Common causes

• Damaged or disconnected wiring to the discharge pressure transducer.
• Failed pressure transducer (open circuit, short circuit, or out-of-range signal).
• Incorrect probe type configured in controller parameters.
• Moisture intrusion into the pressure transducer or its connector.
• Mechanical damage to the pressure probe fitting.

Ask the AskWhiz AI about Carel E406

AskWhiz

online

Hi — I'm the Refrigeration demo. Ask me anything in this domain.

What causes Carel E406?Step-by-step fix for Carel E406?Is Carel E406 safe to ignore?

MessageHelp me troubleshoot Carel E406

Diagnostic steps

1. Locate and inspect the discharge pressure probe

   Identify the pressure transducer on the humidifier discharge line. Inspect the probe body, cable, and connector for visible damage, moisture, or loose connections.

2. Measure probe electrical signal

   With power on, measure the probe output voltage or current at the controller input terminal. Verify it is within the expected range for the installed probe type (e.g., 4–20 mA or 0.5–4.5 V ratiometric).

3. Check parameter configuration for probe type

   Navigate to the probe configuration parameters and confirm the selected probe type matches the physically installed transducer.

4. Replace the discharge pressure probe if faulty

   Install a replacement probe of the correct type and pressure range. Use manufacturer-specified fittings and ensure proper sealing at the process connection.

5. Manually reset E406

   After restoring a valid probe signal, manually reset the alarm by pressing the PRG/reset button. Verify humidifier output resumes normally.

When to call a professional

If the discharge pressure probe tests as functional but E406 persists, the controller input circuit may be defective. Probe replacement on a pressurized humidification system should be performed by a qualified technician with knowledge of system isolation, de-pressurization, and safe re-commissioning procedures.