Warning 88 — Internal sensor signal out of range

What does 88 mean?

The pump's internal sensor is sending a signal that falls outside its normal operating range, indicating a potential sensor issue. The pump may automatically reset and restart once the fault is cleared.

• Faulty internal sensor.
• Loose connection or damaged cable to the internal sensor.
• Malfunction in the sensor's signal processing.

Click steps to track your progress.

1. 1

   Check that the plug and cable for the internal sensor are connected correctly. The sensor is located on the back of the pump housing.

2. 2

   Ensure the connections are clean, secure, and free from corrosion.

3. 3

   If the warning persists, the sensor may need to be replaced, or GRUNDFOS SERVICE should be contacted for assistance.