Common Automotive (& Shorthand) Acronyms

[VileZambonie]

Acronym Definitions

4X2  Four Wheels, Two of which are Drive Wheels
4X4  Four Wheels, Four of which are Drive Wheels

2WD  Two Wheel Drive
4WD  Four Wheel Drive

ABDC  After Bottom Dead Center
ABS  Anti-Lock Brake System  or  Acrylonitrile-Butadiene-Styrene [plastic] (depending on context)
AC  Alternating Current
A/C  Air Conditioning
ACC  Accessory [power]
ad infinitum  "To Infinity" — occurring the same way forever, without end or limit (Latin)
A/F  (also AFR) Air/Fuel Ratio
AFAIK  As Far As I Know
AFB  Aluminum Four Barrel [carburetor]
Ag  Silver [chemical element] (from Latin, argentum) (relevance: a metal component of specialized solder)
a/g  Anything
AIR  Air Injection Reactor (aka, Secondary Air Injection)
aka  (also, AKA and a.k.a.) Also Known As
ALCL  Assembly Line Communications Link
ALDL  Assembly Line Diagnostic Link
ALT  Alternator
AM  Amplitude Modulation
APP  Accelerator Pedal Position [sensor]
ARB  Air Resources Board
ASM  Assembly
A/T  Automatic Transmission or Transaxle
ATDC  After Top Dead Center
ATF  Automatic Transmission Fluid  or  After The Fact (depending on context)
ATM  At The Moment  or  Automatic Teller Machine (depending on context)
AUX  Auxilliary
AVS  Air Valve Secondary [carburetor]
AWD  All-Wheel Drive
AXL  Axle

B1  Bank 1
B1 S1  Bank 1 Sensor 1
B1 S2  Bank 1 Sensor 2
B2  Bank 2
B2 S1  Bank 2 Sensor 1
B2 S2  Bank 2 Sensor 2
B+  Battery Positive [voltage] (constant battery power)
B-  Battery Negative [voltage] (ground)
BARO  Barometric [pressure sensor] (aka, Atmospheric Pressure Sensor)
BAT  (also, BATT)  Battery
BBC  Big Block Chevy [engine]
BBL  (also, bbl) Barrel (usually preceded by the number of throttle plates, 1 - 4, in a throttle body)
BBDC  Before Bottom Dead Center
BCM  Body Control Module
BDC  Bottom Dead Center
BDCI  Bottom Dead Center Intake [stroke]
BDCP  Bottom Dead Center Power [stroke]
BHP  Brake Horsepower
BMW  Bayerische Motoren Werke (Bavarian Motor Works)
BPP  Brake Pedal Position [sensor]
BTC  Before Top Center
BTDC  Before Top Dead Center
BTU  British Thermal Unit
BTW  By The Way

C  Celsius (aka, Centigrade) (temperature)
c-  Centi- (1/100 multiplier)
CAC  Charge Air Cooler (Inter-Cooler)  or  Cab and Chassis (depending on context)
CAN  (also, CAN bus) Controller Area Network [bus]
CARB  California Air Resources Board
carb  Carburetor
C/B  Circuit Breaker
cc  Cubic Centimeters
CCC  (aka, C3) Computer Comand Control
CCOT  Cycling Clutch Orifice Tube [air-conditioning system]
CCW  Counterclockwise [rotation]
CEL  Check Engine Light (equivalent to MIL, SES)
CFI  Continuous Fuel Injection
CFM  Cubic Feet per Minute
CID  Cubic Inch Displacement
CIS  Continuous Injection System
CIS-E  Electronic Continuous Injection System
CKP  Crankshaft Position Sensor
CL  Closed Loop
CLCC  Closed Loop Carburetor Control
cm  Centimeter (1/100 of one meter)
CMP  Camshaft Position [sensor]
CO  Carbon Monoxide
CO2  (also, CO₂) Carbon Dioxide
COC  Coil on Cap
COP  Coil on Plug
CPA  Connector Position Assurance
CPP  Clutch Pedal Position
CPS  Crankshaft Position Sensor  or  Cycles Per Second (archaic usage - see Hz)
CTP  Closed Throttle Position
CTS  Coolant Temperature Sensor
CUCV  Commercial Utility Cargo Vehicle (US Military designation)
CW  Clockwise [rotation]

d-  Deci- (1/10 multiplier)
dB  Decibel (unit of measure for sound)
DC  Direct Current
DFI  Direct Fuel Injection
DIN  "Deutsches Institut für Normung" (translation: "German Institute for Standardization" - the German ISO Body)
DIS  Direct Ignition System (aka, Distributorless Ignition System)
DJ  Dualjet [Rochester carburetor]  or  Disc Jockey (depending on context)
DLC  Data Link Connector
DMM  Digital Multimeter
DOHC  Dual Overhead Cams
DRL  Daytime Running Lamps
DTC  Diagnostic Trouble Code
DTM  Diagnostic Test Mode
DVM  Digital Voltmeter
DVOM  Digital Volt Ohm Meter

EBCM  Electronic Brake Control Module
EBTCM  Electronic Brake Traction Control Module
EC  Engine Control  or  Exhaust [valve] Closing (depending on context)
ECL  Emission Control Label
ECM  Engine Control Module
ECT  Engine Coolant Temperature
ECU  Electronic Control Unit
EFE  Early Fuel Evaporation
EFI  Electronic Fuel Injection
e.g.  (expression)  "For the sake of example,..."  (from Latin, exempli gratia)
e/g  Everything
EGR  Exhaust Gas Recirculation
EGRT  EGR Temperature
EI  Electronic Ignition
EM  Engine Modification
EMI  Electromagnetic Interference
EO  Exhaust [valve] Opening
EOIC  Exhaust [valve] Opening and Intake [valve] Closing (valve adjustment method)
EPROM  Erasable PROM (compare with FPROM, PROM, ROM)
ESC  Electronic Spark Control
ESD  Electrostatic Discharge
EST  Electronic Spark Timing
et al.  (expression)  "...and others"  (from Latin, et alii (masculine form), et aliae (feminine form), et alia (neutral form))
ETC  Electronic Throttle Control
etc.  (expression)  "...and so forth"  (from Latin, et cetera)
EVAP  Evaporative Emission System

F  Fahrenheit (temperature)
F  Farad (unit of measure for electrical capacitance)
FC  Fan Control
FF  Flexible Fuel
FI  Fuel Injection
FM  Frequency Modulation
FP  Fuel Pump
FPR  Fuel Pressure Regulator
FPROM  Flashable PROM (compare with EPROM, PROM, ROM)
FRT  (also, Frt) Front
FSD  Fuel Solenoid Driver (aka, PMD - Pump Mounted Driver) (pertains to diesel engines)
FT  Fuel Trim (Fuel Mixture)
ft. lb.  (also ft-lb)  Foot Pound (unit of measure for torque)
FTP  Federal Test Procedure
FWD  Front Wheel Drive
FWIW  For What It's Worth
FYI  For Your Information

gal  Gallon
GEN  Generator
GLWS  Good Luck With Sale
GLWT  Good Luck With That
GM  General Motors
GMC  General Motors Corporation
GND  Ground
GPM  Grams Per Mile  or  Gallons Per Mile (depending on context)

H20  (also, H₂O) Water
HC  Hydrocarbon
Hg  Mercury [chemical element] (from New Latin, hydrargyrum; Latin, hydrargyrus; Greek, hydrarguros) (aka, quicksilver) (relevance: see Hg")
Hg"  Inches of Mercury (a unit of standard measure for vacuum)
HO2S  Heated Oxygen Sensor
HO2S1  Heated Oxygen Sensor #1; Upstream Heated Oxygen Sensor
HO2S2  Heated Oxygen Sensor #2; Upstream (left or right side), Midstream, or Downstream Heated Oxygen Sensor
HO2S3  Heated Oxygen Sensor #3; Downstream Heated Oxygen Sensor
HP  Horsepower
HTR  Heater
HVAC  Heating Ventilation and A/C System
HVS  High-Voltage Switch
HWB  Hard-Wired Box (a compact PDC/PDM)
Hz  Hertz (unit of measure for frequency equivalent to complete waveform cycles per second)

I+  Ignition Positive [voltage] (switched ignition power - synonymous with IGN)
IA  Intake Air
IAC  Idle Air Control [valve]
IAT  Intake Air Temperature
IC  Ignition Control  or  Intake [valve] Closing  or  Integrated Circuit (depending on context)
ICM  Ignition Control Module
ID  Inside Diameter  or  Identification (depending on context)
IDK  (also, idk) I Don't Know
i.e.  (expression)  "That is to say, ..."  (from Latin, id est)
IFS  Inertia Fuel Shutoff  or  Independent Front Suspension (depending on context)
IG2  Ignition 2 [power]
IGN  Ignition [power - synonymous with I+]
IIR  If I Recall
IIRC  If I Recall Correctly
I/M  Inspection/Maintenance
IMAO  In My Arrogant Opinion (variations: In My Awesome Opinion, In My Actual Opinion, etc)
IMHO  In My Honest Opinion (variation: In My Humble Opinion)
IMNSHO  In My Not-So-Humble Opinion (see IMAO)
IMO  In My Opinion
IMS  If Memory Serves
IMSM  If Memory Serves Me
INJ  Injector
IO  Intake [valve] Opening
I/P  (also, IP) Instrument Panel
IPC  Instrument Panel Cluster
IPT  Internal Pipe Thread
ISC  Idle Speed Control
ISO  International Organization for Standardization (incorrectly aka: International Standards Organization)  or  In Search Of (depending on context)

JK  Just Kidding
JMO  Just My Opinion

k-  Kilo- (1,000 multiplier)
kHz  Kilohertz (1,000 Hertz)
km  Kilometer (1,000 Meters)
kΩ  Kiloohm (1,000 Ohms)
kPa  Kilopascal (1,000 Pascals)
KPH  Kilometers per Hour
kV  (also, kv) Kilovolt (1,000 Volts)
K  Kelvin (temperature)
KOEC  Key On, Engine Cranking
KOEO  Key On, Engine Off
KOER  Key On, Engine Running
KS  Knock Sensor

λ  Lambda (Greek) - the ratio of actual air/fuel ratio (A/F) divided by stoichiometric A/F (for gasoline: λ=1.0 is equivalent to A/F=14.7 or stoichiometric; λ<1.0 ≡ rich A/F; λ>1.0 ≡ lean A/F)
L  Liter
lb. ft.  (also lb-ft) Pound Foot; aka, ft. lb.
LCD  Liquid Crystal Display
LED  Light Emitting Diode
LF  Low Frequency
LH  Left Hand
LOF  Lube, Oil and Filter [engine service]
LPS  Lamps
LSD  Limited Slip Differential
LT  Long-Term [fuel trim]
LWB  Long Wheel Base

M-  Mega- (1,000,000 multiplier)
MΩ  Megaohm (1,000,000 Ohms)
m-  Milli- (1/1,000 multiplier)
ma  Milliamp (1/1,000 of one Ampere)
ml  Milliliter (1/1,000 of one Liter)
mm  Millimeter (1/1,000 of one Meter)
ms  Millisecond (1/1,000 of one Second)
mV  Millivolt (1/1,000 of one Volt)
µ-  Micro- (1/1,000,000 multiplier)
µa  Microamp (1/1,000,000 of one Ampere)
µF  Microfarad (1/1,000,000 of one Farad)
µV  Microvolt (1/1,000,000 of one Volt)
MAF  Mass Airflow Sensor
MAP  Manifold Absolute Pressure [sensor]
MC  Mixture Control
MFI  Multiport Fuel Injection
MHC  Motor Home Chassis (in reference to parts books)
MIL  Malfunction Indicator Lamp (equivalent to CEL, SES)
MJ  Monojet [Rochester carburetor]
MPFI  Multipoint Fuel Injection
MPG  Miles per Gallon
MPH  Miles per Hour
MPT  Male Pipe Thread
MU  Misunderstood word, symbol or concept

n-  Nano- (1/1,000,000,000 multiplier)
N/A  (also, n/a)  Not Applicable
NC  National Coarse [thread] (see UNC)  or  Normally Closed (depending on context)
NF  National Fine [thread] (see UNF)
nF  Nanofarad (1/1,000,000,000 of one Farad)
n/g  Nothing
NL  Not Listed (in reference to parts books)
NLA  No Longer Available
NM  Newton Meter
NO  Normally Open
NOS  New Old Stock
NOX  Oxides of Nitrogen
NPS  National Pipe Straight [thread]
NPT  National Pipe Taper [thread]
NS  Not Serviced  or  Not Stocked (in reference to parts availability)
NSS  Neutral Safety Switch  or  Not Serviced Separately

O2  (also, O₂) Oxygen Molecule
O2S  (also, O₂ Sensor) Oxygen Sensor
OBD  Onboard Diagnostics
OBD I  Onboard Diagnostics, First Generation
OBD II  Onboard Diagnostics, Second Generation
OBS  (also, Obs) Obsolete
OC  Oxidation Catalyst
OD  Outside Diameter
O/D  Overdrive
ODM  Output Device Monitor
ODO  Odometer
OE  Original Equipment
OEM  Original Equipment Manufacturer
OHC  Overhead Cam
OL  Open Loop
OP  Original Post(er)
OPT  Option
OT  Off Topic
Ω  Ohm (Greek letter Omega represents the fundamental unit of electrical resistance)

p-  Pico- (1/1,000,000,000,000 multiplier)
Pa  Pascal (Newtons per Square Meter)
PAIR  Pulse Air Injection Reactor (aka, Pulsed Secondary Air Injection)
Pb  Lead [chemical element] (from Latin, plumbum) (relevance: a common metal component of solder)
P/B  Power Brakes
PCB  (also, PC board) Printed Circuit Board
PCM  Powertrain Control Module (compare with VCM)
PCV  Positive Crankcase Ventilation
PDC  Power Distribution Center  or  Parts Distribution Center (depending on context)
PDM  Power Distribution Module
pF  Picofarad (1/1,000,000,000,000 of one Farad)
PMD  Pump Mounted Driver (aka, FSD - Fuel Solenoid Driver) (pertains to diesel engines)
P/N  Part Number
PNP  Park/Neutral Switch
PO  Previous or Prior Owner
POA  Pilot Operated Absolute [valve]
POE  Point Of Entry (the location where plumbing or wiring enters a cab, housing, or structure)
POV  Point Of View
PPM  Parts per Million
PPS  Pulses Per Second
PRK  Park
PRNDL  Park-Reverse-Neutral-Drive-Low (automatic transmission shift indicator)
PRNODL  Park-Reverse-Neutral-Overdrive-Drive-Low (automatic transmission shift indicator)
PROM  Programmable Read-Only Memory (compare with EPROM, FPROM, ROM)
P/S  Power Steering
PSA  Pressure Switch Assembly  or  Public Service Announcement (depending on context)
PSI  Pounds per Square Inch
PSP  Power Steering Pressure
pt.  Pint
P/U  Pick Up
PUC  Pickup Coil
PVC  PolyVinylChloride [plastic]
PVS  Ported Vacuum Switch
PWM  Pulse Width Modulation
PWR  Power

QJ  Quadrajet [Rochester carburetor]
qt.  Quart

RAM  Random Access Memory
RAP  Retained Accessory Power  or  Rapid Access Panel (depending on context)
RF  Radio Frequency
RFI  Radio Frequency Interference
RH  Right Hand
RLY  Relay
ROFL  Rolling On the Floor Laughing
ROI  Return of Investment
ROM  Read-Only Memory (compare with FPROM, EPROM, PROM)
RPM  Revolutions per Minute
RPO  Regular Production Option
RR  (also, Rr and rr) Rear
RWAL  Rear Wheel Anti-Lock Brake [system]
RWD  Rear Wheel Drive

SAE  Society of Automotive Engineers ("SAE thread" relabeled UNF)
Sb  Antimony [chemical element] (from Latin, stibium) (relevance: a metal component of specialized solder)
SBC  Small Block Chevy [engine]
SC  Supercharger
SCB  Supercharger Bypass
SES  Service Engine Soon [light] (equivalent to CEL, MIL)
SFI  Sequential Fuel Injection
SI  System International (International System of Units)
[sic]  (expression)  quoted "just as" it appears in the source document (from Latin, sicut)
SMD  Surface Mount Device
SMH  Smack My Head, Shaking My Head, Scratching My Head
Sn  Tin [chemical element] (from Latin, stannum) (relevance: a common metal component of electrical solder)
SOHC  Single Overhead Cam
SOL  Solenoid
SOP  Standard Operating Procedure
SPID  Service Parts Identification [label]
SRI  Service Reminder Indicator
SRS  Supplemental Restraint System
SRT  System Readiness Test
ST  Short Term [fuel trim]
STD  (also, Std and std) Standard
SW  (also, Sw and sw) Switch
SWB  Short Wheel Base

TAC  Thermostatic Air Cleaner
TACH  Tachometer
TB  Throttle Body
TBA  Tires, Batteries & Accessories  or  To Be Announced (depending on context)
TBI  Throttle Body Injection
TC  Turbocharger
TCC  Torque Converter Clutch
TCCM  Transfer Case Control Module
TCM  Transmission or Transaxle Control Module
TCS  Transmission Controlled Spark
TDC  Top Dead Center
TDCC  Top Dead Center Compression [stroke]
TDCE  Top Dead Center Exhaust [stroke]
TFP  Throttle Fluid Pressure
THM  (also, TH) Turbo Hydramatic [transmission]
TIA  Thanks In Advance
TLDR  (also TL;DR)  Too Long; Didn't Read  or  Too Long; Don't Read (depending on context)
TMI  Too Much Information
TP  Throttle Position
TPA  Terminal Position Assurance
TPI  Tuned Port Injection  or  Threads Per Inch (depending on context)
TPS  Throttle Position Sensor
TRC  Throttle Return Control         
TSB  Technical Service Bulletin
TTFN  Ta Ta For Now (goodbye until later)
TVS  Thermal Vacuum Switch
TVSV  Thermal Vacuum Switching Valve
TVV  Thermal Vacuum Valve
TWC  Three-Way Catalyst
TWC+OC  Three-Way + Oxidation Catalytic Converter

UHF  Ultrahigh Frequency
UHL  Under Head Length
ULF  Ultralow Frequency
UNC  United National Coarse [thread] (archaic: NC, USS) (incorporates and replaces the USS thread classification)
UNF  United National Fine [thread] (archaic: NF, SAE) (incorporates and replaces the SAE thread classification)
UNEF  United National Extra Fine [thread]
USS  United States Standard ("USS thread" relabeled UNC)  or  United States Ship (a commissioned U.S. Navy ship) (depending on context)

V  Volt
VAT  Volt Amp Tester
VATS  Vehicle Anti-Theft System
VAC  Volts Alternating Current  or  Vacuum [sensor] (depending on context)
VAF  Volume Airflow
VCM  Vehicle Control Module (compare with PCM)
VDC  Volts Direct Current
VDV  Vacuum Delay Valve
VECI  Vehicle Emission Certification Information [label]
VHF  Very High Frequency
VIN  Vehicle Identification Number
VIR  Valve-In-Receiver
VLF  Very Low Frequency
VOM  Volt Ohm Milliammeter
VR  Voltage Regulator
VS  Vehicle Sensor
VSS  Vehicle Speed Sensor
VSV  Vacuum Switching Valve
VTD  Vehicle Theft Deterrent
VTVM  Vacuum Tube Voltmeter
VV  Variable Venturi [carburetor]
VVT  Variable Valve Timing

w/  With
w/i  Within
w/o  Without
WDO  Window
WOT  Wide Open Throttle
WRT  With Respect To
WTB  Want(ed) To Buy
WTH  What The Heck
WU-TWC  Warm Up Three-Way Catalytic Converter

YMMV  Your Method May Vary  or  Your Mileage May Vary (depending on context)

Thanks for the list of automotive acronyms. Very helpful.