The following list of emissions-related acronyms has been standardized by the Society of Automotive Engineers to help servicing today's vehicles easier (or at least more comprehendible). The common terminology, which is part of SAE standard 1930, is being adopted by all vehicle manufacturers.

ACL
Air Cleaner and/or filter

CKP
Crankshaft Position sensor

CL
Closed Loop (feedback mode)

DCL
Data Link Connector

DTC
Diagnostic Trouble Code (fault code)

ECT
Engine Coolant Sensor

EGR
Exhaust Gas Recirculation

EI
Electronic Ignition system

EPROM
Erasable Programmable Read Only Memory

EEPROM
Electronically Erasable Programmable Read Only Memory

EVAP
Evaporative emission control system

HO2S
Heated Oxygen Sensor

IAC
Idle Air Control

IAT
Intake Air Temperature Sensor

IC
Ignition Control (electronic spark timing)

KS
Knock Sensor

LTFT
Long Term Fuel Trim

MAP
Manifold Absolute Pressure sensor

MIL
Malfunction Indicator Lamp (Service Engine Soon lamp)

MFI
Multiport Fuel Injection system

O2S
Oxygen Sensor

OBD
On-Board Diagnostic system check

OC
Oxidation catalyst

OL
Open Loop (feedback mode)

PCM
Powertrain Control Module

PCV
Positive Crankcase Ventilation

PNP
Park Neutral Position switch

RPM
Revolutions per Minute

SFI
Sequential Fuel Injection system

STFT
Short Term Fuel Trim

STD
Scan Tool Data

TCC
Torque Converter Clutch

TP
Throttle Position sensor

TWC
Three-Way Converter (HC, CO & NOX)

TWC+OC
Three-Way Converter plus Oxidation Converter

VIN
Vehicle Identification Number

VSS
Vehicle Speed Sensor

WU-OC
Warm Up Oxidation Converter

WU-TWC
Warm Up Three-Way Converter