Use of nonconforming product 4.13.2 and

The standard requires that where required bp the contract, the proposed use or repair of product which does not conform to specified requirements shall be reported for concession to the customer or customer s representative. The supplementary requirement requires customers to be informed promptly in the event that nonconforming product is shipped. 

The original ISO 9001 requirements and the additional ISO/TS 16949 requirement define two situations one where you know in advance that the product is nonconforming and you want permission for its shipment, the other where at the time of shipment you did not know it was nonconforming and only found out subsequently. 

The only cases where you need to request concession from your customer are when you have deviated from one of the customer requirements and cannot make the product conform. Even when you repair a product, providing it meets all of the customer 

In informing your customer when nonconforming product has been shipped you obviously need to do this immediately you are certain that there is a nonconformity. If you are investigating a suspect nonconformity it only becomes a matter for reporting to your customer when the nonconformity remains suspect after you have concluded your investigations. Alerting your customer every time you think there is a problem will destroy confidence in your organization. Customers appreciate zeal but not paranoid personnel  

The standard requires prior written customer authorization whenever the product or process is different from that currently approved. 

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