Your inline air filter has an element that generally should be changed at least once a year. When the filter element becomes dirty it starts to have a higher pressure drop which can affect the performance of your system. Generally changing the element is as simple as screwing off the filter housing cannister and replacing with a new element. General rule of thumb is to check every 6 months for normal environments. Dirtier environments the element should be checked more often to assure the element is still in good shape and not blocked. Just a little professional tip.....even if your filter housing has a Pressure Differential Gauge or something similar you still should visually inspect the element as sometimes these gauges may not be accurate.