ALDL - Assembly Line Diagnostic Link. Former name for GM (only) Data Link Connector, the connector socket into which the scan tool plug is inserted; sometimes used to refer to any pre-OBD II computer signals
CAN - Controller Area Network
C.A.R.B. - California Air Resources Board
CEL - Check Engine Light
CFI - Continuous Fuel Injection
CO - Carbon Monoxide
DLC - Data Link Connector
Driving Cycle - A specific sequence of start-up, warm-up and driving tasks that tests all OBD II functions
DTC - Diagnostic Trouble Code
ECM - Engine Control Module
ECT - Engine Coolant Temperature
EEC - Electronic Engine Control
EEPROM or E2PROM - Electrically Erasable Programmable Read Only Memory
EFI - Electronic Fuel Injection
EGR - Exhaust Gas Recirculation
EMR - Electronic Module Retard
EPA - Environmental Protection Agency
ESC - Electronic Spark Control
EST - Electronic Spark Timing
FLI - Fuel Level Indicator
HC - Hydrocarbons
HEI - High Energy Ignition
O2S - Oxygen Sensor
IAT - Intake Air Temperature
ISO 9141 - International Standards Organization OBDII communication mode, used by Chrysler and most foreign cars. One of three hardware layers defined by OBD II
J1962 - SAE-established standard for the connector plug layout used for all OBD II scan tools
J1978 - SAE-established standard for OBD II scan tools
J1979 - SAE-established standard for diagnostic test modes
J2012 - SAE-established standard accepted by EPA as the standard test report language for emission tests
MAF - Mass Air Flow
MAP - Manifold Absolute Pressure
MAT - Manifold Air Temperature
MFG - Manufacturer
MIL - Malfunction Indicator Light. The "Check Engine Light" on your dash.
NO2 - Nitrous Oxide
O2 - Oxygen
OBD - On-Board Diagnostics
OBDII or OBD II - Updated On-Board Diagnostics standard effective in cars sold in the US after 1-1-96
Parameters - Readings on scan tools representing functions measured by OBD II and proprietary readings
PCM - Powertrain Control Module
PCV - Positive Crankcase Ventilation
PID - Parameter ID
Proprietary Readings - Parameters shown by on-board computers which are not required by OBD II, but included by manufacturer to assist in trouble-shooting specific vehicles.
PTC - Pending Trouble Code
RPM - Revolutions Per Minute
SAE - Society of Automotive Engineers
Scan Tool - Computer based read-out equipment to display OBD I & OBD II parameters
SES - Service Engine Soon (see MIL)
SFI - Sequential Fuel Injection
Stoichiometric (stoi'chi·o·met'ric) Ratio - Theoretical perfect combustion ratio of 1 part gas to 14.7 parts air
TBI - Throttle Body Injection
TPI - Tuned Port Injection
TPS - Throttle Position Sensor
VAC - Vacuum / Hg
VCM - Vehicle Control Module, the in-car computer that oversees engine management, transmission operation, anti-lock brakes, and other functions not directly related to emissions control
VIN - Vehicle Identification Number
VSS - Vehicle Speed Sensor
WOT - Wide Open Throttle