Display shows Err9 and unit shows no flow even when water is being used

Safety first: Turn off power before removing the control cover. Use caution when working around pressurized plumbing.

Step-by-step checks:

• 1. Confirm meter size setting: In the installer menu, verify that the meter size and pulses-per-gallon (or liter) match the Marlo turbine installed on your unit.
• 2. Inspect turbine magnet: Remove the turbine assembly from the valve outlet. Check that the embedded magnet is intact and firmly seated. If the magnet is missing or cracked, the sensor cannot read flow.
• 3. Clean and reinstall: Clean the turbine and housing, then reinstall, ensuring correct orientation and free spinning.
• 4. Test flow reading: Restore power and run water at a faucet. Observe the display for flow rate. If Err9 returns and no flow is registered, suspect the sensor or control board.

When to replace parts: Replace the Marlo turbine/flow meter assembly if the magnet or wheel is damaged. If a new meter does not resolve Err9, replace the Marlo control board.