Chevrolet B7 2001 Owner's Manual page 127

Engine Air Filter Restriction
Indicator (Diesel Engines)
Your engine has an indicator that lets you know when
the air cleaner filter is dirty and needs to be serviced.
The air filter restriction indicator is located below the air
cleaner on the driver's side of the engine.
R
Caterpillar
Diesel shown
After the air filter is properly serviced, the indicator can
be reset by pushing the button on top of the indicator to
reset it.
4-16
When the yellow indicator
reaches the red ring in the
sight glass, it's time to
service the air filter.
Engine Air Cleaner/Filter
Your GM Maintenance Schedule says when to replace
the air filter.
Gasoline Engine
R
Caterpillar
Diesel Engine