A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
AAI Air Assist Injection - uses an additional injector near each fuel injector that shoots a jet of air into the droplet pattern coming out of the traditional fuel injector. This helps to break droplets into even smaller particles to help them mix with air.
ABS Antilock Brake System
ACC Adaptive Cruise Control
ACM Airbag Control Module
ADC Automatic Distance Control - Uses Radar to detect distance from car in front. Future systems will stop the car when the car in front stops. (VW/Audi) Article
ADBV Anti-DrainBack Valve (on oil filter)
ADR Accident Data Recorder (VW)
A/F Sensor Air/Fuel Ratio Sensor. Sometimes used in place of the front O2 sensor.
AFC Air Flow Control
AFR Air Fuel Ratio
AIR Air Injection Reaction (GM)
AIS Air Injection System
AIS Auto Idle Stop/Automatic idle speed motor
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
AMK Attention Control - A camera monitors the movement of the driver's eyelids, to determine the state of alertness and sends an audio warning when a break is needed. (VW/Audi) Article.
ANB Automatic emergency brake assist. (VW/Audi) Article
AOS Air Oil Separator
APPS Accelerator Position Sensor
ASC Automatic Stability Control (GM)
ASD Automatic Shutdown
ASMS Automotive Stability Management System
ASR Automatic Stability Regulation
AW Aisin-Warner transmission
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
B+ Battery positive voltage (+12 V)
BARO Barometric Pressure (Sensor)
BCM Body Control Module
BUS Multiplex circuits that carry SCP data from module to module and to the DLC
CAI Cold Air Intake - Aftermarket air filter.
CAN Controller Area Network protocol. (ISO 11898, SAE J1939)
Developed by Bosch at the beginning of the eighties as a high-speed, reliable communication protocol for command and control network applications. (CANbus) see also VDB
Some vehicles started using CAN in 2003 (2003 - VW Golf (1K chassis), Audi A8 and A8L (D3 platform, 4E chassis), 2005.5 VW Passat (B6 Platform, 3C chassis)
See: Vetronix
CARB California Air Resources Board
CCD Chrysler Collision Detection
CCM Central Control Module
CCV Crankcase Ventilation or canister control valve
CEL Check Engine Light (See MIL)
CFI Central/Continuous Fuel Injection (a.k.a. Throttle Body Fuel Injection TBI)
CID calibration identification numbers
or Component Identification Data
CKP crankshaft position sensor
CLR DST Distance Since Cleared Diagnostic Codes
CLR TIM Time Since Cleared Diagnostic Codes
CMP camshaft position sensor
CNG Compressed natural gas
CO Carbon Monoxide
CTS Coolant Temperature Sensor
CVN Calibration Verification Number
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
DCP Duty Cycle Purge valve
DF alternator input of regulator circuit
DIY Do-It-Yourself
DLC Diagnostic/Data Link Connectors allow the Code Scanner or Scan Tool to communicate or "plug into" your vehicle's computer(s). Usually under the dash on the middle or drivers side.
DME Digital Motor Electronics
DPF Differential Pressure Feedback - Sensor which measures
DOHC Dual Overhead Cam
DPFE Differential Pressure Feedback EGR sensor ( On Ford OBDII systems).
DRB Diagnostic Readout Box
Driving Cycle A specific sequence of start-up, warm-up and driving tasks that tests all OBD II functions (Details)
DTC Diagnostic Trouble Code - See the DTC page.
DTM Diagnostic Test Modes
DVOM Digital Volt Ohm Meter
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
EATC Electronic Automatic Temperature Control
EATX electronic transmission control module ()
ECC Electronic Climate Control
ECM Engine Control Module- usually the main in-car computer controlling emissions and engine operation (PCM is part of ECM with OBD functions)
ECT Engine Coolant Temperature
ECU Electronic Control Unit (see ECM)
EEC Electronic Engine Control (Ford)
EEC-IV 4th generation EEC system
EEC-V 5th generation EEC system
EEPROM Electronically Erasable Programmable Read Only Memory - chips that allows the PCM to be reprogrammed with revised or updated software.
EFI Electronic Fuel Injection. - Uses an ECM to control the A/F (Air/Fuel) ratios and ignition timing curves.
EGR Exhaust Gas Recirculation - The EGR valve opens at the appropriate time, allowing exhaust gas to enter the intake system.
EGRVR Exhaust Gas Recirculation Vacuum Regulator
EMR Electronic Module Retard
EOBD European on-board diagnostics
EPA Environmental Protection Agency. Federal agency. Office of Transportation and Air Quality (OTAQ) protects public health and the environment by controlling air pollution from motor vehicles.
ESC Electronic Spark Control
ESP Electronic Stability Program. (VW/Audi) Article
EST Electronic Spark Timing
EVAP Evaporation Control (Evaporative Emission Control System) - Fuel Tank emissions.
EVP EGR Valve Position
EVR EGR Vacuum Regulator (EGR solenoid)
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
F2S Follow to Stop - Works with ADC to stop the vehicle automatically the vehicle in front stops. (VW)
Fmep Friction Mean Effective Pressure. Cylinder pressure necessary to overcome friction.
FLASH Process up updating a computer program stored in EEPROM
FLI Fuel Level Indicator
FTP Federal Test Procedure. EPA tersts for emissions output of all fleets of new cars and light duty trucks.
FTP Fuel Tank Pressure
Fuel Trim Engine computer function that keeps the air/fuel mixture as close to the ideal 14.7:1 stoichiometric ratio as possible
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
GOV Governor Control System
HC Hydrocarbons
HC Heading Control (VW)
HEI High Energy Ignition
HO2S HO2S - Heated Oxygen Sensor. A newer version of O2 sensors. They have 3 or 4 wires instead of 2 on the older sensors.
IAC Idle Air Control
IAT Intake Air Temperature
Imep Indicated Mean Effective Pressure: A theoretical average pressure that would have to be present in each cylinder during the power stroke to generate the maximum horsepower possible.
The IMEP parameter is used for misfire monitoring. Computed as torque / engine displacement.
IOD Ignition off draw (fuse in the PDC)
ISC Idle Speed Control
ISO International Organization for Standardization (
ISO 9141 International Standards Organization OBDII communication mode, used by Chrysler and most foreign cars. One of three hardware layers defined by OBD II
IVN In-vehicle network
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
J1850PWM (Recommended Practice for Pass-Thru Vehicle Programming) is an industry standard for flashing emission related ECUs in the service environment.
J1850VPW (Variable Pulse Width Modulated) SAE-established OBD II communication standard used by GM cars and light trucks. 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
J2534-1 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
JTEC Jeep Truck Engine Controller (PCM)
KOEC Key On, Engine Cranking
KOEO Key On, Engine Off
KOER Key On, Engine Running
KS Knock Sensor
Lambda A Lambda sensor measures uburned oxygen in the exhaust.
LDP Leak Detection Pump (Part of EVAP)
LDW Lane departure warning system. (VW/Audi) Article
LIN Local Interconnect Network - A low cost field bus network intended to fit below CAN's functionality. The LIN consortium includes VW/Audi, Daimler-Chrysler and Motorola.
LONGFT Long Term Fuel Trim. ECM memory that adjusts the air/fuel ratio on a semi-permanent basis.
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
MAF Mass Air Flow
MAP Manifold Absolute Pressure
MAT Manifold Air Temperature (Sensor)
MCU Microprocessor Control Unit
MD Modulated Displacement
MDA Modulated Displacement Amplifier
MFG Manufacturer
MFI Multiport Fuel Injection
MIC Mechanical Instrument Cluster
MIL Malfunction Indicator Lamp (Check Engine Light)
MPG Miles Per Gallon (Display Panel)
MPH miles per hour
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
NOx Oxides of Nitrogen
O2 Oxygen
O2 Simulator A device replacing the O2 sensor to avoid a check engine light if you remove the catalytic converter.
O2S Oxygen Sensor. One in the exhaust system before the catalytic converter and one behind it. It fine tunes your mixture to maintain a constant 14.7 -1 air/ fuel ratio which is the optimum mixture.
OBD On-Board Diagnostics (OBD 1 - Ver. 1, OBD 2 - Ver. 2)
OBDII or OBD II Updated On-Board Diagnostics standard effective in cars sold in the US after 1-1-96
OD Overdrive
OEM Original Equipment Manufacturer
OTAQ EPA Office of Transportation and Air Quality (OTAQ) protects public health and the environment by controlling air pollution from motor vehicles.
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
P Code See DTC
Parameters Readings on scan tools representing functions measured by OBD II and proprietary readings
PCM Powertrain Control Module, the on-board computer that controls engine and drive train.
Regulates the fuel system, ignition timing, air-fuel ratio, emission control devices, charging system, speed control, A/C clutch, and idle speed.
See Also ECM
PCV Positive Crankcase Ventilation
PDC Power Distribution Center (Box with fuses under the hood)
PID Parameter identification data
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.
PSI Pounds per Square Inch
PTC Pending Trouble Code
PTU Partial Throttle Unlock
PWM Pulse Width Modulated
PWR Power
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
RAM random access memory
RE Type of Transmission
ROM read only memory
RPM Revolutions Per Minute
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
SAE Society of Automotive Engineers - SAE is a non-profit educational and scientific organization dedicated to advancing mobility technology to better serve humanity. Develop technical information on all forms of self-propelled vehicles including automobiles, trucks and buses, off-highway equipment, aircraft, aerospace vehicles, marine, rail, and transit systems. They set the standards that EPA adopted for OBD.
SAN SEMA Action Network (SAN) is a nationwide partnership between vehicle clubs, enthusiasts and members of the specialty auto parts industry.
SAIR Secondary Air Pump
SBEC Single Board Engine Controller (computer) (PCM)
Scan Tool Computer based read-out equipment to display OBD II parameters
SCI Serial Communications Interface (Chrysler, Motorola)
SCP Standard Corporate Protocol - Module communication (Ford)
SES Service Engine Soon dash light, now referred to as MIL
SFI Sequential Fuel Injection
SHRTFT Short Term Fuel Trim. Short-term air/fuel mixture adjustments. The ECM controls the injector pulse width based on O2S or HO2S signals in order to minimize emissions.
SKIM Smart Key Immobilizer Module
SPD Speed
SPI Serial Peripheral Interface
SRI service reminder indicator
SRS Supplement Restraint System (Airbags)
SRV short runner tuning valve
Stoichiometric ( Stoy'-kee-o-metric) Ratio Theoretical perfect air / fuel ratio of 1 part gas to 14.7 parts air
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
TB Throttle Body
TBI Throttle Body Injection
TC Traction Control
TCC Torque Converter Clutch
TCM transmission or transaxle control module
TCS Traction Control System (GM)
TD Turbo Diesel
TDC Top Dead Center.
TP Throttle Position
TPI Tuned Port Injection
TPS Throttle Position Sensor
TQ Torque measured in pound-feet (lb-ft)
TSB Technical Service Bulletin
TTP Time Triggered Protocol. It is a deterministic protocol intended for SAE class C applications. TTP/C can apparently manage higher data rates than CAN.
TVM Transmission vacuum modulator
UBP UART Based Protocol (UART Based Protocol - Ford)
URD Underdog Racing Development (
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
VAC Vacuum
VAF Vane Air Flow Sensor or Meter
VAG Volkswagen/Audi Group
VAG-COM A PC program to analyze codes for VWs and Audis developed by Uwe Ross (
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
VDB Vehicle Data Bus
VECI Vehicle Emission Control Information
VIN Vehicle Identification Number
VPW Variable Pulse Width (GM)
VPWR Vehicle Power. A switched circuit that provides power to the EEC system. Compare "battery Voltage (B+)."
VREF Reference Voltage. A dedicated circuit that provides approximately a 5.0 volt signal used as a reference by certain sensors.
VSS Vehicle Speed Sensor
VZA Traffic Signs Recognition (VW)
A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z
WOT Wide Open Throttle
WRAF Wide Ratio Air Fuel O2 Sensor
See also: Acronyms at,
Network protocols used in the automotive industry
Acronyms and Definitions at the Ford Truck Enthusiasts Forums
Terms at
Glossary at Telargo
parameter identification data (PID) - Glossary
Auto Information Abbreviation Directory at
Glossary at Pro Racing Simulation
Terms at

last updated 10 Aug 2010