日产PD6、PD60,五十铃6BB1、DA640,三菱DS70A等发动机附装在空气滤清器上或装于空气滤清器和进气歧管之间的滤芯指示器,实际上是一个气压阀门。在滤芯堵塞后,空气滤清器的负压要发生变化,变化了的信号自动地克服弹簧阻力,指示滤芯是应该清洗还是应该更换。日本车辆上装置的空气滤芯指示器,日产公司叫尘埃指示器,五十铃公司叫阻塞指示器 Nissan PD6, PD60, Isuzu 6BB1, DA640, Mitsubishi DS70A and other engines attached to the air filter or installed between the air filter and the intake manifold filter indicator, in fact, is a pressure valve. After the filter plug, the negative pressure of the air filter to change, the change of the signal automatically overcome the spring resistance, indicating that the filter should be cleaned or should be replaced. Japanese cars on the device air filter indicator, Nissan called the dust indicator, Isuzu company called the congestion indicator