What is PID? | PID Full Form | PID Term

OBD-II PIDs (On-board diagnostics Parameter IDs) are codes used to request data from a vehicle, used as a diagnostic tool.
SAE standard J1979 defines many OBD-II PIDs. All on-road vehicles and trucks sold in North America are required to support a subset of these codes, primarily for state mandated emissions inspections. Manufacturers also define additional PIDs specific to their vehicles. Though not mandated, many motorcycles also support OBD-II PIDs.
In 1996, light duty vehicles (less than 8,500 lb or 3,900 kg) were the first to be mandated followed by medium duty vehicles (8,500–14,000 lb or 3,900–6,400 kg) in 2005. They are both required to be accessed through a standardized data link connector defined by SAE J1962.
Heavy duty vehicles (greater than 14,000 lb or 6,400 kg) made after 2010, for sale in the US are allowed to support OBD-II diagnostics through SAE standard J1939-13 (a round diagnostic connector) according to CARB in title 13 CCR 1971.1. Some heavy duty trucks in North America use the SAE J1962 OBD-II diagnostic connector that is common with passenger cars, notably Mack and Volvo Trucks, however they use 29 bit CAN identifiers (unlike 11 bit headers used by passenger cars).