| A |
| 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 |
| 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 |
| C |
| 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 |
| D |
| 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.  obdii.com/connector.html |
| 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 |
| E |
| 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 |
| F |
| 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 |
| G-H |
| 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. |
| I |
| 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 (www.iso.org) |
| 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 |
| J-L |
| 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 |
| M |
| 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 |
| N-O |
| 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 |
| 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 |
| Q-R |
| 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 |
| S |
| 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 |
| T-U |
| 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 (www.urdusa.com) |
| A | B | C | D | E | F | G-I | J-L | M | N-O | P | Q-R | S | T-U | V | W | X-Z |
| V |
| 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 (www.ross-tech.net/vag-com/) |
| 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 |
| W |
| WOT | Wide Open Throttle |
| WRAF | Wide Ratio Air Fuel O2 Sensor |
| X-Z |
See also: 
Home & Garden
