4WD    four wheel drive
A/C    air conditioning
AAI    air assist injection (a valve, fitted to the 4.0 V8)
ABS    anti-lock braking system
ACCM   A/C control module
ACM    audio connectivity module
ACT    air charge temperature (see IAT; an OBD critical sensor)
ADHLS  Axle Deflection Height Levelling System (for self-levelling HIDs)
AE     AutoEnginuity, an advanced OBD tool
AF or AFR    air/fuel ratio
APP    accelerator pedal position (critical sensor(s))
ARTS   adaptive restraint technology system
AWD    all wheel drive
BARO   barometric pressure (an important OBD reading)
BT     Bluetooth
bus    a way of connecting multiple computers so they can talk to each other
CAN    controller area network (often, higher speed OBD protocol mandated by EU & USA)
CAT    catalytic convertor
CATS   (plural of CAT or) computer active technology suspension
CC     cruise or climate control
CCM    climate control module
CEL    check engine light
CHT    cylinder head temperature (not a generic OBD sensor)
CKP    crankshaft sensor (a critical sensor)
CL     closed loop (engine being controlled by feedback from O2 sensors)
CM     control module (often, having a computer inside)
CMP    camshaft sensor (a critical sensor)
COP    coil on plug (where each spark plug has its own coil)
CTS    coolant temperature sensor (see ECT; an OBD critical sensor)
cyl    cylinder
D2B    an optical fibre communications path
DCCV   dual coolant control valve (aka DCFV aka water valve aka heater valve)
DCFV   dual coolant flow valve (aka DCFV aka water valve aka heater valve)
DFCV   dual-flow coolant valve (aka DCCV etc)
DD     daily driver
dead locking    see double locking
DIY    do it yourself
DLC    data link connector (proper name for the OBD connector)
double locking    locking doors and the internal door levers (aka dead locking)
DPF    diesel particulate filter
drive cycle    very complicated driving so PCM exactly relearns car characteristics
DSC    dynamic stability control
DTC    diagnostic trouble code (the way OBD reports problems)
EBA    emergency brake assist
ECT    engine coolant temperature (an OBD critical sensor)
ECU    (non-unique) electronic or engine control unit (such as PCM or TCM)
EGR    exhaust gas recirculation
ELM    an OBD device made by Elm Electronics
ELM327  complex ELM, supporting all common OBD protocols
EML    engine management light (see MIL)
EMS    engine management system
EOBD   European OBD
EOT    engine oil temperature (not a generic OBD sensor)
EPB    electronic (or electric or emergency) park (or parking) brake
ETM    engineering test mode
EVAP   evaporative purge (about control of fuel vapour)
facelift/redesign  (tweaks) 2005/6MY or (major changes) 2002/3MY
 FAQ    frequently asked question
FEM    front electronic module (aka GEM aka GECM)
fob    the (electronics of the) part attached to the vehicle key
FWD    front wheel drive
GECM   general electronic control module (aka GEM aka FEM)
GEM    general electronic module
global opening/closing    opening/closing all doors, windows, sunroof/moonroof
GTR    global technical resource (link from Jaguar home page), now TOPIx
HEGO    heated exhaust gas oxygen (usually about a type of sensor)
HID    high intensity discharge (a type of light)
HO2S   heated oxygen sensor (a critical sensor)
HP     horse power (a measure of power, such as engine output)
HS     high speed (often about a type of CAN)
IAT    intake air temperature (an OBD critical sensor)
IAT2   second IAT (sensor) (commonly, after turbo or SC; a critical sensor)
ICM    instrument cluster (or control) module
IDS    integrated diagnostic system (a dealer tool; very expensive)
IMT    intake manifold tuning (a valve/transducer to change the intake size/shape/flow)
IP     injection (fuel) pressure sensor or instrument pack
IPK    instrument pack (aka instrument cluster or dash)
IR     infrared
ISO    the International Standards Organisation (ISO 9141 is a type of OBD)
JTB    Jaguar Technical Bulletin (see TSB)
JTIS   Jaguar technical information system (computer-based workshop manual)
KAM    keep alive memory (volatile memory where the PCM stores learned values)
key    vehicle key or computer passcode
KS     knock sensor
KWP    keyword protocol (a form of OBD)
LH     left hand (car directions are relative to driver when facing forward)
LHD    left hand drive
LPG    liquified petroleum gas
LSD    limited slip differential
LTFT   long term fuel trim (aka LONGFT), extra fuel being added/subtracted
MAF    mass air flow (a critical OBD sensor)
MAP    manifold absolute pressure (a critical OBD sensor)
MIL    malfunction indicator lamp (sometimes called CEL, EML or SES)
MPG    miles per gallon (N.B. USA gallon is 80% of UK gallon)
MY     model year
NA     naturally (or normally) aspirated (so, not turbo and not SC)
NAS    Jaguar's term for North American Specification
NCM    navigation control module
O2     oxygen
OBD    on board diagnostics (nowadays short for OBD-II or OBD2)
OE     original equipment (as fitted/supplied by the manufacturer)
OEM    original equipment manufacturer
oil    gimme a break
OL     open loop (engine not being controlled by O2 sensors)
PAS    power assisted steering
PATS   passive anti-theft system
PCM    powertrain control module (commonly engine controller but may do more)
PCV    positive crankcase ventilation
PID    parameter ID (a name or number identifying a measured OBD parameter)
PM     particulate matter or private mail
PSE    phone support equipment
PWM    pulse width modulation (a way of controlling electrical output)
RCCM   remote climate control module
RCM    restraints control module
RECM   rear electronic control module (aka REM)
REM    rear electronic module (aka RECM)
rev    reverse or revolution (aka RPM)
RH     right hand (car directions are relative to driver when facing forward)
RHD    right hand drive
RP     restricted performance (aka limp home mode)
RPM    revolutions per minute
RWD    rear wheel drive
RWHP   rear wheel HP
Sat Nav    satellite navigation
SC     supercharger (or supercharged)
SCLM   steering column lock module
SCP    standard corporate protocol (a Ford form of OBD)
SDD    symptom-driven diagnostics (an expensive dealer tool)
SES    service engine soon (see CEL / MIL)
SRS    supplementary restraint system
STFT   short term fuel trim (aka SHRTFT), see LTFT
STR    S-Type R (the supercharged S-Type)
TB     throttle body (a critical, high-precision air-flow control device)
TC     torque convertor or traction control
TCC    torque convertor clutch
TCM    transmission control module
TCS    traction control system
TOPIx  Jaguar's new name for GTR, now at topix.jaguar.jlrext.com
TPS    throttle position sensor (critical OBD sensor(s))
TQ     torque
tranny  transmission
TRQ    torque
TS     twin screw (supercharger)
TSB    technical service bulletin (a fix for/details of problems)
UHEGO  (badly named) so-called "universal" (they aren't) HEGO
UV     ultraviolet
V6     6-cylinder engine arranged as a V of 2 groups of 3
V8     8-cylinder engine arranged as a V of 2 groups of 4
VCT    variable cam timing
VIS    variable intake system (see IMT)
VPW    variable pulse width (a GM OBD protocol)
VSS    vehicle speed sensor
VVT    variable valve timing
WB     wide band (e.g. a type of O2 sensor)
WDS    world diagnostic system (an expensive dealer tool now quite old)
WHP    wheel HP
WOT    wide open throttle (aka kickdown)
WSS    wheel speed sensor
ZF     a German company (maker of gearboxes, steering racks and much more)