ISO 12345:2013 specifies cleanliness assessment procedures for evaluating the amount of debris found within the clean side of diesel fuel injection assemblies, which could lead to a reduction in the system's operational effectiveness.

While other International Standards, e.g. the ISO 16232 series, relate to cleanliness of components used in road vehicle fluid circuits, ISO 12345:2013 is focused on diesel fuel injection assemblies as supplied to diesel engine manufacturers or the service market.