Corrective action removes the cause of a problem that already happened, so it does not happen again. Preventive action removes the cause of a problem that has not happened yet. Since its 2015 edition, ISO 9001 no longer has a separate preventive action requirement. It is handled through risk-based thinking instead: tools like the PFMEA, error-proofing and read across. Many companies still use the term CAPA for both.
The short version
| Corrective action | Preventive action | |
|---|---|---|
| Starts from | A problem that happened: a complaint, a defect, an audit finding | A risk: a failure that could happen but has not |
| Goal | Stop it happening again | Stop it happening at all |
| Typical tools | 8D, 5 Why, fishbone, effectiveness check | PFMEA, error-proofing, read across, lessons learned |
| Proof | The problem does not come back | The risk rating drops and the failure never shows up |
Example of each
- Corrective. Weld nuts spun loose at the customer. The cause was electrode tips dressed by the clock instead of by weld count. The action: dress every 400 welds with an interlock. See the 8D report example.
- Preventive. The second welder in the plant has never had a complaint, but it has the same time-based tip dress. Changing it before it fails is preventive. That move is often called read across.
Where preventive action went
Older editions of ISO 9001 had a clause called preventive action. The 2015 edition dropped it and asked for risk-based thinking across the whole system instead, on the idea that the whole quality system should be preventive. In practice the work did not change: you still look for risks and act on them. It just lives in your PFMEA, your planning and your reviews rather than on a separate form.
Mistakes that blur the two
- Calling containment a corrective action. Sorting stock protects the customer. It does not remove a cause.
- Closing a corrective action with no read across. If the same cause can exist on another line, part or supplier, check it while the evidence is fresh.
- Waiting for a failure to update the PFMEA. A near miss or a problem on a similar part is reason enough.
ISO 9001 was revised in 2026 and IATF 16949 has a new edition planned. This page covers what holds across editions. Check your certification body and customer requirements for the edition and transition dates that apply to you.