2003 GMC Sierra 1500 Pickup Owner's Manual - Page 398

Engine Air Cleaner/Filter The air cleanedfilter assevbly has an indicator, if equipped, that lets you know when the engine air cleaner/filter is dirty and needs to be serviced. The air cleanedfilter indicator is located on the air cleaner cover. See Engine Compartment Overview on page 5-12 for more information on location. See Part B: Owner Checks and Services on page 6- 1I to determine when to check the indicator. The service window A with the percentage scale shows the amount of engine air cleaner/filter life used. When both service window A and service window B turn orange, replace the engine air cleaner/filter. The air cleanedfilter assembly is located on the front corner of the engine compartment on the passenger's side of the vehicle. See Engine Compartment Overview on page 5-12 for more information on location. After changing the air filter, press the top button on the indicator to reset it. 5-23