Grundfos Grundfos Pump Error Code 21

Grundfos Pump Major Hardware

Model: Grundfos Pump | Code: 21

Applicable Systems
MAGNA1

Symptoms

Motor fault. The pump motor has a fault detected by the controller.

Possible Causes

  • Motor winding failure or degradation
  • Motor bearing failure causing drag

Troubleshooting Steps

  1. Step 1: Check the motor winding resistance and insulation
    Winding is shorted or insulation is degraded
  2. Step 2: Inspect the motor bearings for wear
    Bearings are worn or damaged

How to Reset

To reset: Repair or replace the motor, then reset the controller.

Source: Grundfos Pump Troubleshooting Guide, Grundfos Group

Category: Pump