This really depends on the type of gate opener and if it is a new install or an existing one that is starting to have an issue. Mighty Mules, GTOs, and the E-S Allegiant have fixed open limit. If it is a new install then the unit was not installed in the open position as it should have been. If it is an existing then possibly the brackets have shifted or the limit switch is broken. Liftmaster LA400 and LA412 have programmed stop points. For new or existing try programming the open position again. If it does not work then there could be a rev counter or board issue. Estate Swings have adjustable open limit switches for the ES1000, 300, 500 and 1600 series. For a new install adjust your limit switch so the piston retracts less. For an existing, check to be sure brackets have not moved and then check to see if the piston is moving past the limit.