Preventive Action is the countermeasure taken before a defect occurs, anticipating a potential failure and installing a control that prevents it. It sits alongside Corrective Action in ISO-style quality systems and is the more mature discipline: fixing what hasn't broken yet.
FMEA (Failure Modes and Effects Analysis) systematically identifies what could go wrong before it does. Trend analysis on quality data shows drifts that would eventually become failures. Lessons learned from similar processes elsewhere. Near-miss reports from the shop floor. Each source feeds a list of potential failures worth preventing.
Corrective action responds to a problem that has occurred. Preventive action responds to a problem that has not yet occurred but could. Both are essential; healthy quality systems have far more preventive actions than corrective, because they are catching potential failures before they become real ones.
Preventing every possible failure is impossible. Preventive action lists must be prioritized: focus on failures with the highest severity, the highest likelihood and the lowest current detectability. FMEA's Risk Priority Number captures this combination and helps direct effort where it matters most.
Preventive action is the discipline of learning from what hasn't happened yet. Combined with FMEA, trend analysis and near-miss reporting, it moves quality from reactive to proactive, and dramatically reduces the number of defects that would otherwise have reached the customer.
