K 3500 Truck 4WD V8-6.5L DSL Turbo VIN S (1999)
Air Cleaner Restriction Indicator: Description and Operation
Air Cleaner Restriction Indicator
The air cleaner restriction indicator is located on the intake duct between the air cleaner assembly and the Mass Air Flow (MAF) sensor.
If the area inside of the clear section is green, no air filter service is required. If the area inside the clear section is orange and Change Air Filter appears,
replace the air filter.