Do the CNG systems need a specific maintenance?
CNG systems do not need any specific maintenance. Following the instructions indicated by the use and maintenance booklet of the system is suggested. In italy, a specific tag required by the law (CNG cylinders fund committee) shows safety and validity information about cylinders installed on the car, necessary to refuel. CNG cylinders must be replaced after 4 or 5 years from its final test according to the compliant regulation.
Please check the related laws in force in your country.