ISO 15501-1:2016 specifies the minimum safety requirements applicable for the functionality of CNG on-board fuel systems intended for use on the types of motor vehicles defined in ISO 3833. This document is applicable to vehicles using compressed natural gas in accordance with ISO 15403, including mono-fuel, bi-fuel or dual-fuel applications, original-production and converted vehicles. All matters relating to the skills of installers and converters have been excluded from this document.