A service interval is not specified for the fill valve filter. Its condition depends on fuel quality. Use of CNG with excessive amounts of contaminants or compressor oil will increase the frequency of service. A contaminated or clogged fill valve filter will not affect the emissions or the driveability of the vehicle. However, refueling time may increase. If the customer notes an increase in refueling time, inspect the fill valve filter. Service if necessary. Refer to Fill Valve Replacement or Fill Valve Filter Replacement .