Safety first: Unplug the unit and place it in bypass. Open a faucet to relieve pressure.

Steps to check:

1. Remove turbine sensor: Pull the retaining clip and gently remove the turbine sensor from the outlet port of the valve.
2. Inspect turbine wheel: Ensure the wheel spins freely and is not obstructed by scale or debris. Clean with water and a soft brush.
3. Verify installation direction: Reinstall the turbine and sensor in the correct orientation as indicated by arrows on the valve body.
4. Check wiring and connector: Inspect the sensor cable and connector at the control board. Repair any damage and reseat the connector.
5. Test flow reading: Restore water and power. Run water at a faucet and confirm the display shows flow or that the usage counter increments. If E4 persists, replace the turbine sensor.

When to call a technician: If a new sensor does not resolve E4, the control board may have a failed input circuit.

Display shows E4 and water usage is not recorded (no gallons counted)

Possible Causes