Definition
The FMEA score for whether the controls in place can catch a failure before it reaches the next step; a higher score means it is harder to catch.
In detail
Detection runs against intuition: the better the detection capability, the lower the score. It is scored against the controls that exist today, not the ones planned; writing in an inspection that has not been implemented is the most common way this column is faked. Lowering detection is the fastest of the three routes, but it does not reduce failures — it only keeps them from escaping, so it cannot replace lowering occurrence. The detection method itself must first pass measurement system analysis.
Example in practice
An out-of-tolerance dimension was previously caught by sampling at final inspection, rated 8. After in-line 100 percent checking backed by a measurement system analysis it is re-rated 2 and the RPN falls from 288 to 72, yet the team keeps the occurrence action in the plan.