CodeRegistry
Brands
  1. Home
  2. Wilo
  3. Yonos PICO Pumps
  4. E04
About·Privacy·Terms

CodeRegistry — Your global library for technical solutions.

For your safety: always follow the equipment manufacturer’s official manuals. CodeRegistry is an independent help site and is not affiliated with the brands listed here.

E04

E04 - Undervoltage detected

Wilo · Yonos PICO Pumps

What does E04 mean?

The LED display shows E04, indicating that the power supply voltage to the pump is too low. The pump may switch off.

Common Causes

  • Low mains voltage detected

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the mains voltage supply.

  2. 2

    Ensure the power supply is within the pump's specified operating range.

  3. 3

    Consult a qualified electrician if the voltage remains low.

Browse all codes in this manual (17)
Verified technical data. Last updated: April 2026

Related Faults

Bars bottom to top blinkBars bottom to top blink - Pump venting function activeBuilding does not get warmBuilding does not get warm - Heating output too lowE05E05 - Overvoltage detected
Source: Wilo Yonos PICO Pumps
Open Manual (Page 20)Search more codes in this manual