Emission Control Abbreviations: "H"

HAC: High Altitude Compensator
HAFS: Heated Air Fuel Ratio Sensor
HAI: Hot Air Intake
HAS: High Altitude System
HC: Hydrocarbons
HCAC-VSV: Hydrocarbon Absorber Catalyst Vacuum Switching Valve
HDC: Heavy Duty Cooling
HDC-CTO: HDC Coolant Temperature Override
HFM-SFI: Hot Film Engine Management SFI
HIC: Hot Idle Compensator
HIM: Heated Intake Manifold
HO: High Output
HO2S: Heated Oxygen Sensor
HP: High Performance
HP: Horsepower
HPCA: Housing Pressure Cold Advance
HSC: High Swirl Combustion