Your preventive action procedure must explain how you:
> review potential problems
> decide the potential cause of the problem
> decide an appropriate course of action to stop the problem occurring
> put the plan into action
> ensure that the preventive action has solved the potential problem
Preventive action is a pro-active procedure ie dealing with the problem BEFORE it happens.
This ISO 9000 procedure makes more sense if you see as the FIRST requirement in ISO 9001. It also helps to know that ISO 9004 calls this procedure "Loss Prevention".
The preventive action procedure may include:
> applying a proven corrective action (8.5.2) to other areas of the business
> being aware of changes (5.6)
> disaster recovery plan - what will you do if your building burns down, you lose a major customer, a raw material is no longer available, etc. ?
To understand what an auditor will look for, see the Auditing Preventive Action paper on ISO 9000 Auditing Practices Group site