The Model LRA Swing Gate Operator running APeX Controller firmware Version 1.0 or lower can experience difficulty detecting arm presence when used not installed on a gate or on very small or lightweight gates, resulting in an EN12 error code.
Upgrading the Controller to firmware Version 1.1 or higher will eliminate this issue.
A field solution for installations running Version 1.0 or lower firmware is to install a 100 ohm, 10 Watt resistor (i.e. Radio Shack P/N 271-0135) across Terminals #1 and #2 on the controller terminal strip (this is parallel to the motor connections). After installing the resistor, re-program the Controller’s force settings.