The Short Answer - They tell us both what’s inside your catalytic converter or DPF

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Instead of manufacturers making a different housing every time they changed the contents, allowing future recyclers to tell the difference,

They imprinted a PPM code which recyclers could later enter into a test sample database

These databases are full of previously tested examples of that PPM code, giving a more accurate expectation of recovery

Without checking this code, the buyer in most cases doesn’t know what the piece is really dworth in order to start purchase conversation