OBD2 Scanner Abbreviations: Your Guide to Decoding Car Diagnostic Codes

Understanding Obd2 Scanner Abbreviations is crucial for anyone involved in vehicle diagnostics and repair. With the standardization of On-Board Diagnostics II (OBD2) systems in modern vehicles, a plethora of acronyms and initialisms have become commonplace. This comprehensive guide will help you decipher these abbreviations, providing a clear understanding of what they mean and how they relate to your vehicle’s health.

Common OBD2 Scanner Abbreviations Explained

OBD2 scanners communicate with your vehicle’s computer system to retrieve diagnostic information. This information is often presented using abbreviated terms. Let’s break down some of the most frequently encountered abbreviations, categorized for easier understanding.

Engine & Emission Control Abbreviations

These abbreviations are related to the engine’s operation and emission control systems, which are central to OBD2 diagnostics.

AFC – Air Flow Control: Refers to systems that manage the volume of air entering the engine.
AIR – Secondary Air Injection: A system that pumps fresh air into the exhaust to reduce emissions.
CARB – California Air Resources Board: The leading emissions regulation agency, setting standards that often influence federal regulations.
CFI – Central Fuel Injection (a.k.a. Throttle Body Fuel Injection TBI): An early type of fuel injection where fuel is injected at a central point, like a carburetor.
CO – Carbon Monoxide: A toxic gas produced by incomplete combustion. Monitoring CO levels is vital for emissions and engine health.
CO2 – Carbon Dioxide: A greenhouse gas, also monitored in emissions testing.
ECT – Engine Coolant Temperature: Crucial for engine management, as temperature affects engine performance and emissions.
ECU – Engine Control Unit: Often used interchangeably with ECM, referring to the computer controlling the engine.
ECM – Engine Control Module: The primary computer in the vehicle that manages engine and emission systems.
EEC – Electronic Engine Control: A general term for electronic systems managing the engine.
EGR – Exhaust Gas Recirculation: A system to reduce NOx emissions by recirculating exhaust gas back into the intake.
EGRT – EGR Temperature: Temperature sensor for the Exhaust Gas Recirculation system.
EI – Electronic Ignition: Ignition system controlled electronically, rather than mechanically.
EMR – Electronic Module Retard: Electronic system to retard ignition timing, often for knock prevention.
EPA – Environmental Protection Agency: The US federal agency responsible for environmental protection, including vehicle emissions standards.
ESC – Electronic Spark Control: Electronic system managing spark timing.
EST – Electronic Spark Timing: Electronic control over the timing of the spark plugs.
EVAP – Evaporative Emission System: System to prevent fuel vapors from escaping into the atmosphere.
HC – Hydrocarbons: Unburnt fuel in the exhaust, a regulated emission.
LEV – Low Emission Vehicle: Vehicle certified to meet low emission standards.
NOx – Oxides of Nitrogen: Harmful emissions formed at high combustion temperatures.
OC – Oxidation Catalyst: Catalytic converter that reduces hydrocarbons (HC) and carbon monoxide (CO).
PCV – Positive Crankcase Ventilation: System to recirculate crankcase gases back into the intake, reducing emissions and engine sludge.
SFI – Sequential Fuel Injection: Fuel injection system that injects fuel individually for each cylinder in a timed sequence.
TBI – Throttle Body Injection: Another term for Central Fuel Injection (CFI).
TWC – Three Way Catalyst: Advanced catalytic converter that reduces NOx, HC, and CO simultaneously.
ULEV – Ultra Low Emission Vehicle: Vehicle certified to meet ultra-low emission standards.
ZEV – Zero Emission Vehicle: Vehicle that produces no tailpipe emissions.

Sensor & Component Abbreviations

These abbreviations represent sensors and components that OBD2 systems monitor to ensure proper vehicle operation.

B+ – Battery Positive Voltage: Indicates voltage from the positive terminal of the battery.
BARO – Barometric Pressure: Atmospheric pressure, used by the ECM for altitude compensation.
CKP – Crankshaft Position Sensor: Sensor that monitors the position and speed of the crankshaft.
CMP – Camshaft Position Sensor: Sensor that monitors the position of the camshaft.
CPP – Clutch Pedal Position: Sensor indicating the position of the clutch pedal.
DEPS – Digital Engine Position Sensor: A digital sensor for engine position.
DPFE – Differential Pressure Feedback EGR sensor: (On Ford OBDII systems) Measures pressure difference in the EGR system.
FLI – Fuel Level Indicator: Sensor that measures the fuel level in the tank.
FP – Fuel Pump: The pump that delivers fuel from the tank to the engine.
HO2S – Heated Oxygen Sensor: Oxygen sensor with a heater to reach operating temperature quickly.
HO2S1 – Upstream Heated Oxygen Sensor: Oxygen sensor located before the catalytic converter.
HO2S2 – Downstream Heated Oxygen Sensor: Oxygen sensor located after the catalytic converter.
HO2S3 – Downstream Heated Oxygen Sensor: In systems with multiple downstream sensors, this refers to a further downstream sensor.
IAT – Intake Air Temperature: Sensor measuring the temperature of the air entering the intake manifold.
IFS – Inertia Fuel Shutoff: Safety switch that cuts off fuel supply in case of a collision.
KS – Knock Sensor: Sensor that detects engine knocking or detonation.
MAF – Mass Air Flow: Sensor that measures the mass of air entering the engine.
MAP – Manifold Absolute Pressure: Sensor measuring the pressure in the intake manifold.
MAT – Manifold Air Temperature: Another term for Intake Air Temperature (IAT).
MDP – Manifold Differential Pressure: Measures pressure difference in the intake manifold.
O2S – Oxygen Sensor: Sensor measuring the oxygen content in the exhaust gas.
PSP – Power Steering Pressure: Sensor monitoring pressure in the power steering system.
TPS – Throttle Position Sensor: Sensor that measures the position of the throttle plate.
VAF – Volume Airflow: Sensor that measures the volume of air entering the engine (similar to MAF).
VSS – Vehicle Speed Sensor: Sensor that measures the speed of the vehicle.

Communication & Standards Abbreviations

These terms are related to communication protocols and standards within the OBD2 system.

ALDL – Assembly Line Diagnostic Link: Precursor to OBD2, used by GM.
CAN – Controller Area Network: The communication network within the vehicle for modules to exchange data.
DLC – Data Link Connector: The 16-pin connector where the OBD2 scanner plugs in.
ISO 9141 – International Standards Organization OBDII communication mode: One of the OBD2 communication protocols, used by Chrysler and many foreign makes.
J1850PWM – (Pulse Width Modulated) SAE-established OBD II communication standard: OBD2 protocol used by Ford.
J1850VPW – (Variable Pulse Width Modulated) SAE-established OBD II communication standard: OBD2 protocol used by GM.
J1939 – SAE standard for higher-speed CAN bus diagnostics (heavy-duty vehicles): While not strictly OBD2, often found in related contexts.
J1962 – SAE-established standard for the connector plug layout: Standardizes the physical OBD2 connector.
J1978 – SAE-established standard for OBD II scan tools: Standards for OBD2 scan tools.
J1979 – SAE-established standard for diagnostic test modes: Standards for OBD2 diagnostic tests.
J2012 – SAE-established standard for diagnostic trouble codes: Standardizes DTC codes.
OBD – On-Board Diagnostics: General term for vehicle self-diagnostic systems.
OBD I – Onboard Diagnostics Generation One: The precursor to OBD2.
OBD II or OBD2 – Onboard Diagnostics, Second Generation: The standardized system used in modern vehicles.
PID – Parameter ID: Code used to request specific data parameters from the vehicle’s computer.
SAE – Society of Automotive Engineers: Organization that sets standards for the automotive industry, including OBD2.
VIN – Vehicle Identification Number: Unique identifier for each vehicle.

General Automotive Abbreviations

These are general automotive terms that might appear in diagnostic contexts.

A/C – Air Conditioning: Vehicle’s air conditioning system.
AC – Air Cleaner: Air filter for the engine intake.
A/T – Automatic Transmission or Transaxle: Automatic transmission system.
BCM – Body Control Module: Computer module controlling body electronics.
CAC – Charge Air Cooler: Intercooler for turbocharged engines.
CL – Closed Loop: Engine control mode where the computer uses sensor feedback (especially O2 sensors) to adjust fuel mixture.
CTOX – Continuous Trap Oxidizer: Type of emissions control device.
CTP – Closed Throttle Position: Indicates the throttle is fully closed.
DFCO – Decel Fuel Cut-Off Mode: Fuel saving strategy during deceleration.
DFI – Direct Fuel Injection: Fuel injection directly into the cylinder.
DIC – Driver Information Center: Display providing vehicle information to the driver.
DTM – Diagnostic Test Mode: Specific modes for running diagnostic tests.
EBCM – Electronic Brake Control Module: Computer module controlling electronic braking systems like ABS.
EBTCM – Electronic Brake Traction Control Module: Module for brake and traction control.
EC – Engine Control: General term for engine management.
ECL – Engine Coolant Level: Indicates the level of coolant in the engine.
EEPROM – Electrically Erasable Programmable Read Only Memory: Type of memory in car computers.
EFE – Early Fuel Evaporation: System to improve fuel vaporization during cold starts.
EPROM – Erasable Programmable Read Only Memory: Another type of memory.
FC – Fan Control: System for controlling engine cooling fans.
FF – Flexible Fuel: Vehicle capable of running on different fuel mixtures (e.g., ethanol).
FT – Fuel Trim: Adjustments made to the base fuel mixture by the computer.
FTP – Federal Test Procedure: Standardized emissions testing procedure.
GCM – Governor Control Module: Module for speed governing.
GEN – Generator (Alternator): Vehicle’s electrical generator.
GND – Ground: Electrical ground connection.
H20 – Water: Chemical formula for water, relevant in coolant contexts.
HVAC – Heating Ventilation and Air Conditioning System: Vehicle’s climate control system.
IA – Intake Air: Air entering the engine intake.
IAC – Idle Air Control: System for controlling engine idle speed.
IC – Ignition Control Circuit: Circuit controlling the ignition system.
ICM – Ignition Control Module: Module controlling the ignition system.
I/M – Inspection/Maintenance: Emissions and safety inspection programs.
I/M 240 – Inspection/Maintenance 240 emissions test: Specific type of emissions test.
IPC – Instrument Panel Cluster: Vehicle’s dashboard instrument cluster.
ISC – Idle Speed Control: System for controlling idle speed.
KOEC – Key On, Engine Cranking: Ignition key position during engine start.
KOEO – Key On, Engine Off: Ignition key is on, but engine is not running.
KOER – Key On, Engine Running: Ignition key is on and engine is running.
KSM – Knock Sensor Module: Module associated with knock sensors.
LT – Long Term Fuel Trim: Long-term adjustments to fuel mixture.
MC – Mixture Control: System for controlling air-fuel mixture.
MFG – Manufacturer: Vehicle manufacturer.
MIL – Malfunction Indicator Light (Check Engine Light): Light indicating a problem detected by OBD2.
MPH – Miles Per Hour: Unit of speed.
ODM – Output Device Monitor: OBD2 system monitoring output devices.
OL – Open Loop: Engine control mode where the computer does not use sensor feedback to adjust fuel mixture (e.g., during warm-up).
OSC – Oxygen Sensor Storage: Refers to oxygen storage capacity in catalytic converters.
PAIR – Pulsed Secondary Air Injection: Type of secondary air injection system.
PCM – Powertrain Control Module: Computer module that controls both engine and transmission.
PNP – Park/Neutral Switch: Switch indicating if the transmission is in Park or Neutral.
PROM – Program Read Only Memory: Type of memory.
PSA – Pressure Switch Assembly: Assembly containing pressure switches.
RAM – Random Access Memory: Type of computer memory.
RM – Relay Module: Module containing relays.
ROM – Read Only Memory: Type of computer memory.
RPM – Revolutions Per Minute (Engine Speed): Engine speed measurement.
SC – Supercharger: Forced induction system.
SCB – Supercharger Bypass (Wastegate): Bypass valve for supercharger.
SDM – Sensing Diagnostic Mode: Diagnostic mode related to sensing systems.
SRI – Service Reminder Indicator: Light indicating a service is due.
SRT – System Readiness Test: Tests to verify OBD2 system readiness.
ST – Short Term Fuel Trim: Short-term adjustments to fuel mixture.
TB – Throttle Body: Part of the intake system containing the throttle plate.
TC – Turbocharger: Forced induction system.
TCC – Torque Converter Clutch: Clutch in the torque converter of an automatic transmission.
TCM – Transmission or Transaxle Control Module: Computer module controlling the transmission.
TFP – Throttle Fluid Pressure: Pressure in the transmission fluid system related to throttle position.
TP – Throttle Position: Position of the throttle plate.
TVV – Thermal Vacuum Valve: Vacuum valve controlled by temperature.
VR – Voltage Regulator: Regulates voltage in the electrical system.
VS – Vehicle Sensor: General term for vehicle sensors.
WOT – Wide Open Throttle: Throttle plate fully open.
WU-TWC – Warm Up Three Way Catalytic Converter: Catalytic converter designed to heat up quickly.

Technical Terms Related to OBD2 Scanners

Beyond abbreviations, understanding certain technical terms is also essential for effective OBD2 diagnostics.

Baud Rate: The speed of data transmission in bits per second, relevant to communication between modules.
Bus: The communication network (like CAN bus) that allows modules in the vehicle to communicate.
CAN (Controller Area Network) Bus: The primary communication network in modern vehicles.
Closed Loop: Engine operating mode where the computer uses feedback from sensors like oxygen sensors to control fuel mixture for optimal emissions and performance.
Code Reader: A basic OBD2 tool that reads and clears diagnostic trouble codes (DTCs).
Downstream O2 sensor: The oxygen sensor located after the catalytic converter, primarily monitoring catalyst efficiency.
Drive Cycle: A specific sequence of driving conditions needed to run OBD2 monitors and confirm repairs.
Enable Criteria: Conditions that must be met for an OBD2 monitor to run.
Fuel Trim: Fine-tuning of the air-fuel mixture, including short-term and long-term adjustments.
Loaded Mode Testing: Emissions testing performed under simulated driving load, often using a dynamometer.
Misfire Detection: OBD2 system’s ability to detect engine misfires, crucial for emissions and engine health.
Monitor: A self-diagnostic test performed by the OBD2 system on various components and systems.
Open Loop: Engine operating mode where the computer uses pre-programmed values for fuel mixture, without sensor feedback.
Parameters: Data values read by a scan tool, representing sensor readings and system status.
Pending Trouble Code (PTC): A code that is detected but not yet confirmed as a permanent fault.
Proprietary Readings: Vehicle-specific data parameters beyond standard OBD2 requirements.
Readiness Code or Flag: Indicates whether an OBD2 monitor has run and completed its test.
Scan Tool: A more advanced diagnostic tool than a code reader, capable of reading codes, sensor data, and performing bidirectional tests.
Stoichiometric Ratio: The ideal air-fuel mixture ratio for combustion (14.7:1 for gasoline).
Trip: A driving session long enough for OBD2 monitors to run.
Upstream O2 sensor: Oxygen sensor located before the catalytic converter, used for fuel control.
Warm-up Cycle: Engine warm-up process from a cold start to a specific temperature.

Conclusion

This guide provides a comprehensive overview of OBD2 scanner abbreviations and technical terms. Understanding these terms is essential for accurately interpreting diagnostic information and effectively troubleshooting vehicle issues. By familiarizing yourself with these abbreviations, you can better utilize OBD2 scanners and gain a deeper understanding of your vehicle’s diagnostic data. This knowledge empowers you to communicate more effectively with mechanics, perform your own basic diagnostics, and ultimately keep your vehicle running smoothly and efficiently.