Warning 88 — Internal sensor fault

What does 88 mean?

The pump is receiving a signal from its internal sensor that is outside the normal operating range. This is a warning and does not activate the alarm relay.

• The plug and cable for the internal sensor are not connected correctly.
• A faulty internal sensor.

Click steps to track your progress.

1. 1

   Switch off the power supply to the pump.

2. 2

   Locate the internal sensor (on the back of the pump housing) and ensure its plug and cable are connected correctly and securely.

3. 3

   Carefully inspect the sensor cable for any visible damage.

4. 4

   If the warning persists, contact Grundfos Service; the sensor may need replacement.