Diesel Acronyms

Common Acronyms used in Diesel Diagnostic & Troubleshooting Guides

Troubleshooting guides, diagnostic procedures, and technical information in general rely on an array of acronyms to describe various systems, sensors, processes, and procedures. The list below includes definitions of common acronyms that you may come across; acronyms are alphabetized for your convenience.

AAT - Ambient air temperature

ABS - Anti-lock brake system

ACC - Accessory key position

APPS - Accelerator pedal position sensor, sometimes simply accelerator position sensor (APS).

BW - BorgWarner, popular transfer case manufacturer and drivetrain component supplier for various automakers.

B5 - Common biodiesel blend; 5% biodiesel, 95% petroleum diesel.

B10 - Method of approximating diesel engine service life, see what is B10 and B50 Life.

B20 - Common biodiesel blend; 20% biodiesel, 80% petroleum diesel.

B50 - Method of approximating diesel engine service life, see what is B10 and B50 Life.

CAC - Charge-air-cooler, synonymous with intercooler or aftercooler.

CAN - Controller area network, protocol for OBD-II diagnostic systems.

CEL - Check engine light

CDR - Crankcase depression regulator

CKP - Crankshaft position sensor

CPS - Camshaft position sensor

CP3 - Injection pump produced by Bosch, found in various Duramax and common rail Cummins engines.

CP4 - Injection pump produced by Bosch, found in various modern common rail diesels.

CMP - Camshaft position, often referring to the CPS or parameter ID.

CR - Common rail

CTD - Cummins turbo diesel

DB2 - Injection pump produced by Stanadyne, found on GM and International IDI diesels.

DB4 - Injection pump produced by Stanadyne, found on 6.5L GM turbodiesels.

DEF - Diesel exhaust fluid

DI - Direct injection

DIT - Direct injection turbocharged

DOC - Diesel oxidation catalyst

DPF - Diesel particulate filter

DTC - Diagnostic trouble code

EBP - Exhaust backpressure, alternatively EP (exhaust pressure)

EBV or EBPV - Exhaust backpressure valve; a valve located behind the turbine outlet of a turbocharger that closes when an engine is cold to help bring it to operating temperature more rapidly.

ECM - Engine control module

ECT - Engine coolant temperature

ECU - engine control unit

EGR - Exhaust gas recirculation

EGT - Exhaust gas temperature, typically measured before the turbine inlet of the turbocharger.

EOT - Engine oil temperature

EP or EBP- Exhaust pressure, exhaust backpressure

FFM - Fuel filter manager; a fuel filter housing assembly (water separator, fuel heater, etc) manufactured by Stanadyne for various applications. One style in particular is found on 6.5L GM diesels.

FICM - Fuel injection control module, controls injection events on a 6.0L Power Stroke.

FSD - Fuel system driver

GCWR - Gross combined weight rating

GP - Glow plug

GPCM - Glow plug control module

GPM - Glow plug module

GTWR - Gross trailer weight rating

GVWR - Gross vehicle weight rating

HFCM - Horizontal fuel conditioning module; the chassis (frame) mounted combination fuel-water separator, fuel filter system found on 6.0L and 6.4L Power Stroke diesels.

IAT - Intake air temperature, typically used in reference to a sensor in the air intake system.

IC - Intercooler, synonymous with charge-air-cooler or aftercooler.

ICP - Injector control pressure, often used in reference to the ICP sensor found on 7.3L and 6.0L Power Stroke diesel engines. The sensor reads the pressure in the high pressure oil circuit.

IDI - Indirect injection

IDM - injector driver module

IDS - Integrated diagnostic system

IP - Injection pump or injector pump

IPR - Injector pressure regulator, an actuator found on 7.3L and 6.0L Power Stroke diesel engines. The IPR valve controls the injector control pressure by directing oil pressure to bleed off into the crankcase as necessary.

ISB - Interact system B (B-series), name of the 5.9L, 24 valve Cummins.

HEUI - Hydraulic electronic unit injector

HPOP - High pressure oil pump, referring to the heart of the high pressure oil circuit on 7.3L and 6.0L Power Stroke diesels.

KOEO - Key on engine off

KOER - Key on engine running

LP - Lift pump, referring to the low pressure fuel pump on a diesel engine.

LSD - Low sulfur diesel

MAP - Manifold absolute pressure, the absolute pressure as measured in the intake manifold. Not to be confused with gauge pressure, absolute pressure reads ~14.7 psi at sea level.

MGP - Manifold gauge pressure, the gauge pressure as measured in the intake manifold. This is synonymous with turbocharger boost pressure. See also MAP. As opposed to absolute pressure, gauge pressure is calibrated to measure 0 psi at sea level.

MIL - Malfunction indicator lamp

NOx - Nitrous oxides; used as shorthand for the compounds nitric oxide (NO) and nitrogen dioxide (NO2), both of which are an important part of diesel emission regulations. Not to be confused with nitrous oxide. May be used in reference to a NOx sensor, an integral part of SCR emissions systems.

NP - New Process Gear, popular manufacturer of transmission and transfer cases for various automakers. Purchased by Chrysler and later merged with GM's Muncie division.

N-m - Newton meters, a metric measurement of torque (convertible to ft-lbs/lb-ft)

NV - New Venture Gear, a joint venture between GM and Chrysler resulting in the production of various transmissions and transfer cases. Company was essentially a merger of GM's Muncie and Chrysler's New Process Gear divisions.

OBD - On-board diagnostic system, used in reference to the OBD-I and OBD-II diagnostic system protocols.

OBS - Old body style, used to describe the 1994 to 1997 Ford F-Series.

OPS - Oil pressure sensor, or alternatively oil pressure switch when used in reference to 1992 - 1995 model year GMC/Chevrolet pickups equipped with the 6.5L GM diesel. On these early model year 6.5L engines, the oil pressure sensor doubles as a switch that delivers power to the lift pump. For replacement information, see: 6.5L GM Diesel OPS replacement procedures

PCM - Powertrain control module

PID - Parameter ID, referencing the ID's of various engine parameters that can be monitored using diagnostic equipment.

PMD - Pump mounted driver

RPM - Revolutions per minute; engine speed.

SCR - Selective catalytic reduction

TFT - Transmission fluid temperature

TPS - Throttle position sensor (APPS is more common in diesel applications as there is technically not a traditional "throttle" in most applications)

TSB - Technical service bulletin

ULSD - Ultra low sulfur diesel

VGT - Variable geometry turbocharger

VSS - Vehicle speed sensor

WOT - Wide open throttle