Automotive Glossary

Automotive Glossary

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E.C. (E)

European Commission (Executive).


Electronic Control Unit."


Electronic Control Unit.


Electro Motive Force.


Electrically Erasable Programmable Read Only Memory


Electronic Air Control Valve

Early Fuel Evaporation

Early fuel evaporation system using a heater element below a carburettor to heat the intake air and improve atomisation at cold engine speeds. Improves driveability and reduces harmful exhaust emissions.

Earth (Ground)

The electrical termination for components connected into a vehicle direct current earth return circuit. On mains electricity a safety route for an electrical short circuit used as a means of protecting people or electrical components from electrical overload.(Ground - US term)

Earth (Ground) Cable

The battery cable connecting the return side of a vehicle circuit to a terminal on the battery where a ground return circuit is used. (Ground - US term).

Earth Switching

Used to describe a circuit where the switch breaks the earth side of the circuit instead of the supply side.

Earth Switcing

See Earth Switching!


Electronically controlled automatic transmission.


Electronic Brake Control Module


Electronic Body Module


Electronic Control Assembly


Electronic Control of Automatic Transmission


Off centre. Usually refers to a rotating component with the operational part rotating about the central axis of the shaft. An example is a round cam offset from the shaft axis.


Engine control module. The electronic control module for engine management systems.


Engine coolant temperature sensor or sender.


Electronic Control Unit.


Electronic Diesel Control.


Painting technique where full panels are sprayed without blending into masked off adjacent panelwork, or where panels are removed from the vehicle to be painted


Electronic distributor or distributorless ignition system.


Explanation Demonstration Participation – a reminder of a good way to teach something practical to somebody.


Electronic engine control module.


Electronically Erasable Programmable Read Only Memory


Electronic Fuel Control


Electronic Fuel Control Assembly


Early fuel evaporation system using a heater element below a carburettor to heat the intake air and improve atomisation at cold engine speeds. Improves driveability and reduces harmful exhaust emissions.


A measure of effectiveness given as a ratio, percentage or decimal value (co-efficient) based on actual and possible performance.

Efficiency (energy)

Energy conversion efficiency is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The useful output may be electric power, mechanical work, or heat.


To produce work without wasting time and energy.


A force or action that tries to achieve something.


Electronic fuel injection using sensors, an electronic control unit and fuel injectors to spray fuel into a central throttle body or the inlet ports. Provides very close control of fuel mixture under all operating conditions.


Exhaust Gas Oxygen Sensor. Also HEGO - Heated Exhaust Gas Oxygen Sensor, EOS Exhaust Oxygen Sensor and Lambda sensor. Provides information to the fuel system ECU on the oxygen content in the exhaust gas.


Exhaust gas recirculation. An emission control system that uses an exhaust gas feed into the intake air stream to reduce the mass of oxygen in the air charge and limit the formation of harmful oxides.


EGR Valve Position Sensor


EGR Temperature


Electronic Ignition

Elastic Limit

Amount of deflection in a spring that can be tolerated before permanent deformation occurs.


The property of materials that can deform and return to their original shape without permanent deformation.

Electric Field

Area round an electric charge in which an electric force is exerted.

Electrical Energy

The potential of electricity to do work.

Electro Motive Force (e.m.f.)

Voltage or pressure in a circuit.

Electro Motive Force (emf.)

Electrical energy available to a circuit at the battery or generator.

Electro Plating

Coating with chromium, silver, etc. by electrolysis.

Electro-coating (Electrophoretic coating)

Electro-coating is an organic coating method that uses electrical current to deposit paint onto vehicle bodies, part, or other assembled products.


Usually a metallic conductor which conducts electricity into a liquid, a gas, a vacuum or on to the surface of a solid.


A method by which paint is applied electrically by immersing electrodes and the work to be painted in a water-based paint and applying a direct electrical current to them.


A combination of electrical and hydraulic control systems.


Electroluminescence (EL) is an optical and electrical phenomenon in which a material emits light in response to an electric current passed through it, or to a strong electric field. It is used on in car entertainment systems and instruments on some vehicles.


A liquid that conducts electricity. Battery acid is a good example.


A magnet formed by a soft iron core and an electrical winding about the core. Becomes a magnet when an electrical current flows through the windings.


See electromagnet.

Electromagnetic Oscillation

Changes from one value to another in a circuit. Usually produces a sine wave output or similar.

Electromagnetic Solenoid

A solenoid (coil of wire) that is used to operate an actuator such as a fuel injection.

Electromagnetic Valve

A valve that is operated by a coil of wire, which becomes magnetic when switched on.


Electrons form the outer shell layers of atoms and orbit the protons and neutrons in the nucleus. The electrons have negative polarity and are electrically negative in opposition to the positive charge of the protons.

Electron Shell

Term used to describe the orbit of electrons round a nucleus.


Electrical systems operated or controlled by semi-conductor devices.

Electronic Control

System usually based round an electronic control unit where the operation of the system is pre-programmed.

Electronic Ignition

Petrol ignition system in which switching semi-conductors make and break the low tension circuit.


Describes the electrical state of something as in static (not flowing) electricity.


The basic form of a material.


Electronic Mail. Messages sent from one person to another electronically via a computer.


Electromagnetic compatibility. EMC requirements stipulate that a device shall not cause interference within itself or in other devices, or be susceptible to interference from other devices.

Emergency Brake

A legal requirement for all vehicles provided by a split hydraulic circuit or a mechanically operated parking brake.

Emery Paper

Carborundum grit on a backing sheet.


Electromagnetic Interference

Emission Control

Systems on the vehicle to control (limit) toxic emission.


Systems on the vehicle to control (limit) toxic emission.


Terminal of a transistor that becomes conductive when the base is energised.


A way of expressing emotions in online communication. E.g., :-)


Electronic Module Retard


A suspension of fine particles in a liquid. The dispersed particles may be binder, pigments, or other ingredients.

Emulsion Tube

Combined main and compensating jet tubes in a carburettor with provision for drawing air into the fuel flow to create an emulsion at higher engine speeds, thus preventing over-richness and improving fuel distribution.


EN European Standard e.g. BS EN 50342-2:2007 relates to: Lead-acid starter batteries and is a combined British and European standard (Dimensions of batteries and marking of terminals)


A paint type which forms a film by absorbing oxygen during curing. Characterised by slow drying and having a highly glossy, finished appearance without polishing.

End Float

Longitudinal play in shaft, intentional or otherwise.

End Play

Alternative term for end float. Longitudinal play in shaft, intentional or otherwise.


An ability to perform work. SI unit is the 'Joule'.


The act of making a connection between two gears of through a clutch.

Engaging Pin

A simple pin used to make a drive connection.

Engaging Plunger

General term to describe a plunger that engages something! Often part of a gearbox.

Engine Analyser

Complex test equipment used to check a variety of engine operating functions and conditions. An oscilloscope is usually included.

Engine Analyzer

Complex test equipment used to check a variety of engine operating functions and conditions. An oscilloscope is usually included.

Engine Block

Main part of the engine that contains the cylinders.

Engine Compartment

The space under the bonnet!

Engine Load

How hard the engine is having to work. For example, accelerating uphill creates a high load.

Engine Management

General term used to describe the control of engine operating functions such as ignition and fuelling. Usually related to electronic control.

Engine Map

A three dimensional map held in a microprocessor that provides an optimum set of values for the control of ignition timing, ignition dwell period and fuel quantities for all engine operating conditions.

Engine Speed Sensor

Provides information on engine speed to engine management systems (transducer).

Engine Support Beams

A bar that is used to support an engine, for example, after the transmission has been removed.

Engine Temp. Sensor

Engine temperature sender unit for temperature gauge and engine management systems (thermistor).

Engine Torque

The amount of turning force produced by an engine. Usually quoted at a set speed.


Process of increasing the mixture strength / reducing the air fuel ratio.


European Onboard Diagnostics


EOS Exhaust Oxygen Sensor. Provides information to the fuel system ECU on the oxygen content in the exhaust gas. Also EGO Exhaust Gas Oxygen Sensor, HEGO Heated Exhaust Gas Oxygen Sensor and Lambda sensor.


Environmental Protection Agency

Epicyclic Gear

See Epicyclical Gearing.

Epicyclical Gearing

A gear system, consisting in basic form of an internally toothed annulus or ring gear and a central externally toothed sun wheel, with usually three or four planet wheels or gears meshing with the sun wheel and annulus. The planet wheels are often carried as a unit on a planet carrier or spider. Holding the rotation of the planet carrier, annulus or sun wheel will provide a transmission ratio between the two remaining elements. Planetary gear sets can be coupled to increase the available number of ratios.


An epitrochoid is a shape traced by a point attached to a circle of radius r rolling around the outside of a fixed circle of radius R, where the point is a distance d from the centre of the exterior circle. It is the shape of the cylinder in a Wankel engine.


EGR Valve Position Sensor


A type of paint, adhesive or plastic noted for high mechanical strength, good adhesion and excellent chemical resistance.


Erasable Programmable Read Only Memory.


Exhaust Electronic Pressure Transducer.


Electronic Spark Control


Electronic Spark Timing


A type of organic compound used as active solvents.


An opinion or judgement.


Emergency Testing – the process by which testing may continue when the computerised system is not available due to a wide scale failure affecting a significant number of VTSs.

Etch Primer

Primer with an acid (usually Phosphoric) content. The purpose of the Etch primer in a coating system is to improve the adhesion and corrosion performance of the undercoat system. Their use is recommended when working with ferrous substrates, and essential on non-ferrous substrates


The process of a strong chemical cutting into unprotected parts of a metal.


Ethyl-alcohol produced from starches and sugar plants and used as an octane enhancer.

Ethyl Acetate

A fast evaporating ester solvent.

Ethyl Alcohol

An inexpensive, fast evaporating solvent or diluent.

Ethylene Glycol

Anti-freeze. Chemical used to lower freezing point of coolant.


The European Union (EU) is an economic and political union of 27 (as at 2010) member states, located primarily in Europe. Committed to regional integration, the EU was established by the Treaty of Maastricht on 1 November 1993.

Evaluation Circuit

An electronic circuit used to decide a course of action.


Emission control system that uses a charcoal canister to prevent fuel tank vapours from venting to the atmosphere. The vapours are drawn into the engine during specific running conditions to purge the canister.


The change from liquid to a gas. When solvents leave a wet paint film, they usually do so by evaporation.

Evaporation Rate

The speed at which any liquid evaporates.

Evaporative Canister

A canister usually containing charcoal that prevents emissions from the fuel tank due to evaporation.


A radiator in the air conditioning system fitted in the heater and A/C housing. The refrigerant passes through the pipes in the evaporator and vaporises to absorb heat and therefore cool the air stream flowing into the vehicle passenger compartment.


This is what a candidates needs to produce to prove they have the skills required.


EGR Valve Position Sensor


Electronic vacuum regulator solenoid on EGR system.

Excess Pressure Valve

A pressure relief valve that opens if pressure exceeds a set value. Often for safety reasons.

Exhaust Blow-by

Gases from the exhaust bypassing a component, for example, the piston rings or a valve in a turbocharger.

Exhaust Emissions

Substances vented into the atmosphere from an exhaust system.

Exhaust Gas Analyser

An instrument for measuring the constituent gases in the exhaust.

Exhaust Gas Analyzer

See Exhaust Gas Analyser.

Exhaust Gas Recirculation

An emission control system that uses an exhaust gas feed into the intake air stream to reduce the mass of oxygen in the air charge and limit the formation of harmful oxides.

Exhaust Manifold

Heat resisting ducting that connects the exhaust ports of an engine to an exhaust pipe.

Exhaust Ports

Outlets in the cylinder head for the exhaust after the valve opens. In a two-stroke engine the ports are in the side of the cylinder.

Exhaust Stroke

The last stroke of the four stroke cycle when the burnt gases are expelled to the atmosphere.


An increase in size. For example, when a metal rod is heated it increases in length and diameter. Opposite of contraction.

Expansion Box

Open muffler in the exhaust system to reduce the noise.

Extender Pigment

An inert, usually colourless and semi-transparent pigment used in paints to fortify and lower the price of pigment systems.

Extension Housing

Usually describes an extra housing on the rear of a transmission gearbox.

External assessment

A test set externally to check portfolio evidence.

External Customer

One outside of an organisation.

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