You will get an error 201 when the machine is not detecting flow when there should be flow.

1. Make sure the valves feeding this flowmeter are opening.

2. Make sure the pump(s) are on and working properly. Check for airlock.

3. Make sure any filters in line are not plugged.

4. Is the meter getting powered?

5. If it is a gear meter, make sure the gears spin freely. Gear Meter Repair