1999 GMC Suburban P0102 Code: What Does 'Mass or Volume Circuit Low Input' Mean and How to Test MAF Sensor?

I own a 1999 GMC Suburban with a persistent P0102 diagnostic trouble code. The error message 'mass or volume circuit low input' is confusing — what does it actually mean? Several online sources suggest this code may be related to the Mass Air Flow (MAF) sensor. If that's correct, I need to know how to properly test the MAF sensor to determine if it's functioning correctly. The P0102 code indicates that the engine control module (ECM) is detecting a lower-than-expected airflow compared to the engine's RPM, throttle position (TPS), and manifold absolute pressure (MAP) inputs. In my vehicle, which has a 5.7L Vortec engine, the MAF sensor is digital (FM type). Digital sensors are generally less susceptible to electrical connection issues, so signal loss due to wiring problems is unlikely. That said, the issue may not be with the MAF sensor itself but rather with airflow entering the engine without being measured. I should inspect for loose, split, cracked, or disconnected intake ducts and ensure the intake air horn seals properly to the throttle body. Additionally, I need to check if the Charcoal Canister Vent (CCV) fresh air hose is connected or damaged, or whether the PCV valve is correctly attached to the rocker cover or its hose is missing. I'm currently investigating potential intake leaks and have confirmed there are no aftermarket air filters or modifications to the original intake system.