Participant's Workbook, De

Aftersales Training Participant's Workbook. Diesel engine.

BMW Service

The information contained in this Workbook is intended solely for the participants of this seminar run by BMW Aftersales Training. Refer to the latest relevant BMW Service information for any changes/supplements to the Technical Data. Information status: December 2007

Contact: [email protected] © 2007 2007 BMW AG München, Germany Reprints of this publication or its parts require the written approval of BMW AG, München VS-12 Aftersales Training

The information contained in this Workbook is intended solely for the participants of this seminar run by BMW Aftersales Training. Refer to the latest relevant BMW Service information for any changes/supplements to the Technical Data. Information status: December 2007

Contact: [email protected] © 2007 2007 BMW AG München, Germany Reprints of this publication or its parts require the written approval of BMW AG, München VS-12 Aftersales Training

Participant's Workbook. Diesel engine.

Notes on this Workbook Symbols used The following symbols are used in this Workbook to facilitate better comprehension and to draw attention to important information.

3 contains information for better understanding of the described systems and their functions. 1 identifies the end of a note.

Information status: BMW vehicles conform to the highest safety and quality standards. Changes in terms of environmental protection, protection, customer benefits and design render necessary continuous development of systems and components. Consequently, Consequently, this may result in deviations between this Product Information and the vehicles available during the training course. This documentation relates exclusively to left-hand drive vehicles with European specifications. Some controls or components are in part arranged differently in right-hand drive vehicles than shown on the grap graphi hics cs in the the Prod Produc uctt Info Inform rmat atio ion. n. Furt Furthe herr diff differ eren ence cess may may aris arise e as the the result of the equipment variants used in specific markets or countries. Additional sources of information Furt Furthe herr info inform rmat atio ion n on the the indi indivi vidu dual al topi topics cs can can be foun found d in the the foll follow owin ing g sources of information: - Product Information - Owner's Handbook - BMW diagnosis system - Workshop systems documentation - SBT BMW Service Technology

Contents. Diesel engine. Training Information on how to use this workbook Fuel-and-air mixing Intake air and exhaust system Fuel system Engine electrics Diagnostics

1 1 2 10 23 37 42

Training. Diesel engine.

Information on how to use this workbook This workbook helps trainers and participants to achieve the learning objectives of this module. The focal points of the basic modules are: • the ability to process customer orders in a professional manner and with appreciation of the process as a whole • the building of specialist, diagnostics and repair competencies • the development of a feeling of responsibility for continuously checking the quality of one's own work and improving it. The workbook offers a means of working independently through tasks similar to customer orders. However, the workbook is also designed to lend support to, and provide a framework for, tasks led by the trainer. Additionally, there is space to make your own notes and write down important information. Unlike the Basic Information document, which contains a great deal of background information, the workbook is intended to record experiences and impressions from training.

1

Fuel-and-air mixing Diesel engines can be driven on various fuels. • Diesel • Bio-diesel • SunDiesel = BtL fuel (biomass to liquid) • Natural diesel = vegetable oil. They have to be adapted for the type of fuel in each case. This documentation exclusively addresses diesel engines driven on diesel.

In a diesel engine, air is compressed and injected directly into the combustion chamber at the end of the compression stroke. "Internal fuel/air mixing" occurs in which the injected fuel is mixed with air and ignites as a result of the high temperature caused by compression. For this to occur, the injected fuel must be supplied in the correct quantity and quality (optimum atomized form). That is necessary in order that the engine produces the required power output and that complete combustion takes place.

Chemical conditions Chemical conditions include those chemical properties of the diesel fuel that have an effect on the combustion process.

• Complete combustion • Ignitability • Flashpoint • Density • Sulphur.

These include: Notes:

2

1. Indicate the special characteristics and properties that you think belong to the different chemical conditions listed. Complete combustion: 4

Each fuel requires a specific amount of air to achieve complete combustion.

4

Diesel fuel consists of carbon atoms and hydrogen atoms that are converted into carbon dioxide (CO2) and water (H2O) during combustion.

4

Optimum fuel combustion is achieved in the presence of an air surplus.

4

Diesel fuel evaporates at approximately 55 ° C.

Ignitability: 4

Ignitability is a measure of when the fuel begins to evaporate.

4

The higher the cetane number, the more ignitable the fuel.

4

The lower the cetane number, the more ignitable the fuel.

Flashpoint: 4

The flashpoint is a measure of when the fuel spontaneously ignites.

4

Diesel fuel has a flashpoint above 55 ° C.

Density: 4

The density of the fuel has a bearing on engine output.

4

Cold fuel has a lower density.

Sulphur: 4

The sulphur in the fuel reduces particle emissions.

4

A higher sulphur content in the fuel results in higher particle emission levels.

4

The sulphur content of the fuel is controlled by legislation.

Fuel-Air Ratio The fuel-air ratio indicates the composition of Practical fuel-air ratio the fuel-and-air mixture. It specifies how many The practical fuel-air ratio indicates how many parts of fuel are mixed with how many parts of kg of air are actually supplied to the engine per air. kg of fuel. The power output, fuel consumption and the If the proportion of fuel is smaller, e.g. 1 : 13, exhaust emissions all depend largely on the there is a shortage of air. This is referred to as fuel-air ratio. Complete combustion takes a "rich" mixture. place at a precisely defined calculated fuel-air ratio, the theoretical fuel-air ratio.

Theoretical fuel-air ratio (stoichiometric ratio) This defines the air mass required for complete combustion of 1 kg of fuel. That is why it is also called the theoretical air requirement. For diesel, the theoretical fuel-air ratio is 1 : 14.5. That means that complete combustion of 1 kg of diesel requires 14.5 kg of air.

3

Air ratio λ (lambda) The air ratio λ is the ratio between the mass of air actually supplied and the theoretical air requirement. 2. Construct the formula for calculating the air ratio. Air ratio λ =

If the engine is supplied with precisely 14.5 kg of air, i.e. exactly the theoretical air requirement, then λ = 1. That is demonstrated by the formula: 14.5 kg

λ =

14.5 kg

=1

Now let's return to the earlier examples: With a rich mixture of 1 : 13, i.e. 13 kg of air to 1 kg of diesel, the lambda value is as follows: 13.0 kg

λ =

14.5 kg

= 0.9

With a lean mixture of 1 : 16, i.e. 16 kg of air per kg of diesel, the resulting lambda value is: 16.0 kg

λ =

14.5 kg

= 1.1

3. Which statements are correct? 4

If the proportion of fuel is greater, e.g. 1 : 16, there is a surplus of air. The mixture is then "lean".

4

A "rich" mixture is where the fuel is characterized by a surplus of air.

4

The practical fuel-air ratio indicates the actual air mass supplied.

4. Write the air ratio in the following table. Air content

Lambda

Air deficiency

λ

1

Air surplus

λ

1

Notes:

4

Effect of air ratio The air ratio has a direct effect on an engine's power output/torque, its fuel consumption and the composition of the exhaust. The following graphics show the relationship between λ , the exhaust gas recirculation rate and the pollutant emissions.

1 - Exhaust gas recirculation rate and air ratio

Index

Explanation

A

Air ratio λ =

B

Exhaust gas recirculation rate 2 - Exhaust gas recirculation rate and pollutant emissions

Index

Explanation

A

Pollutant emission

B

Exhaust gas recirculation rate

CO

Carbon monoxide

HC

Hydrocarbon

NOx

Nitrogen oxides

5. What information can you deduce from the graphs above?

5

Operating conditions Different engine operating conditions require certain mixture compositions (quality).

Therefore, fuel-and-air mixing adjusts to the particular operating conditions.

6. Name the various operating conditions and explain what needs to be taken into consideration for each one of them. Operating condition Cold starting

Warming up

Medium power

Full power

Transition/acceleration

Idling

Overrunning

6

Particularities

Exhaust composition The fuel-and-air mixture undergoes chemical changes in the course of combustion. In the process its composition is altered.

The following graphic shows the composition of the exhaust gas of a diesel engine operated on diesel fuel directly after combustion (without exhaust re-treatment).

7. Assign the item numbers to the correct descriptions in the table.

Index

Explanation

Index

Explanation

Carbon dioxide (CO2)

Sulphur dioxide (SO2)

Nitrogen (N2)

Oxygen (O2)

Water (H2O)

Hydrocarbon (HC)

Particles

Nitrogen oxides (NOx)

Carbon monoxide (CO) Notes:

7

8. What are the particularities of the listed constituent elements of the emissions? Constituent element of emissions Nitrogen (N2)

Carbon dioxide (CO2)

Carbon monoxide (CO)

Sulphur dioxide (SO2)

Particles

Hydrocarbon (HC)

Nitrogen oxides (NOx)

Oxygen (O2)

8

Particularities

How mixture preparation works At least three subsystems are essential to the mixture preparation process: • Air intake and exhaust system • Fuel system • Engine electronics. With direct fuel injection, the fuel has to be atomized in the correct amount and at the right time and then injected into the combustion chamber in the correct mixture ratio. The interaction of the three systems above is designed to ensure that these conditions are fulfilled 3 - Direct injection

9. What are the tasks of each of these systems? System

Tasks

Air intake and exhaust system

Fuel system

Fuel system

9

Intake air and exhaust system 10. Assign the item numbers to the correct components.

10

Index

Explanation

Index

Explanation

Boost-pressure sensor

Exhaust turbocharger with VNT

Diesel particulate filter (DPF)

Charge-air temperature sensor

Throttle valve

Exhaust temperature sensor

Intake silencer (air cleaner)

Digital Diesel Electronics (DDE)

Centre silencer

Charge-air cooler

EGR (exhaust gas recirculation) valve and distance sensor

Hot-film air mass meter (HFM)

Exhaust back pressure sensor

EGR cooler

N47D20O0 engine

Rear silencer

EGR bypass valve

Oxygen sensor

Oxidation catalytic converter

Air intake system The unfiltered air is referred to as raw air. The intake air system is divided into an area in which the air is not yet filtered, known as the unfiltered air duct. Downstream of the filter

element, the raw air is cleaned and is, therefore, now referred to as purified air. From the filter element onwards, the system is called a purified air system.

11. On the vehicle and dismantled engine, trace the route of the intake air from the intake snorkel to the cylinder head. In the relevant order, note down the components through which the intake air flows.

11

Intake silencer 12. What are the functions and tasks of the intake silencer?

13. Carry out a filter replacement on the vehicle and make notes detailing your procedure.

Notes:

Exhaust turbocharger 14. What are the benefits of turbocharging?

12

4

Lower fuel consumption by comparison with a naturally aspirated engine of equivalent capacity

4

The otherwise unused exhaust gas energy is used for turbocharging

4

The turbocharged engine consumes less fuel than an equally powerful naturally aspirated engine

4

The exhaust turbocharger is subject to a replacement interval

4

The torque curve can be plotted more favourably

4

Engines can operate with a greater air surplus than a naturally aspirated engine

4

The exhaust turbocharger comprises a turbine and a compressor, both located on the one shaft.

15. Assign the item numbers to the correct components.

Index Explanation 16

8

Index Explanation

Oil return flange

Oil supply

Turbine wheel

Impeller

Outlet to catalytic converter

Compressor housing

Sealing plate

Wastegate valve

Partial-vacuum canister

Turbine housing

13

Piston ring seal

3

Heat shield

7

Safety plate

14

Main bearing

4

Bearing housing

Outlet to charge air cooler

15

Bearing bushing

Input from exhaust manifold

Input from intake silencer

13

Charge-air cooler 16. Why is a charge-air cooler used? 4

So that the engine is cooled by the intake air

4

Because air is heated both during compression and by the exhaust turbocharger

4

To increase the density of the intake air

4

Because it means the exhaust turbocharger does not have to work as hard

4

Because it means engine output can be increased.

Notes:

Throttle valve A throttle valve is required in all diesel engines equipped with a diesel particle filter. By throttling the intake air, the throttle valve

ensures that the elevated exhaust gas temperatures required for diesel particle filter regeneration are achieved.

17. What other tasks does the throttle valve have?

Notes:

14

Intake manifold The intake manifold is usually made of plastic. Inside it, the air is branched off the individual

cylinders. In addition, the ducts to each individual cylinder branch off further into swirl ducts and tangential ducts.

18. Remove the intake manifold in accordance with the Repair Instructions. Note down your procedure (work sequence).

Notes:

15

Swirl flaps

Engine/s

The swirl flap closes the tangential port in order to generate a stronger swirl of air via the swirl port in the combustion chamber at lower engine speeds. With increasing engine speed, they open to ensure cylinder charging through the tangential port.

M67D44O1

X

-

M57D30T2

-

X

M57TU2

-

X

N47D20T0

X

-

N47

X

-

M47TU2

-

X

The following table shows which type of actuation is used for the different engines.

Electric


Index Explanation

Notes:

16

Index

Explanation

Tangential port

Swirl flap

Swirl port

Exhaust duct

Pneumatic

Exhaust system The exhaust system takes care of removal of the burned gases. It also incorporates exhaust treatment systems that remove harmful emissions from the exhaust. The type of

exhaust re-treatment depends on the engine model. One aim of the exhaust system is to reduce flow resistance to a minimum so as to achieve optimum engine performance.

20. Onthe vehicle and dismantled engine,trace the route ofthe exhaust gas fromthe cylinder head to the tailpipe. In the relevant order, note down the components through which the exhaust gas flows.

Notes:

17

Exhaust gas recirculation 21. As you have surely noticed by now, there is another duct that branches off from the exhaust manifold. This duct returnsthe exhaustgas to the intake air system. What reason could there be for this?

Notes:

Oxidation catalytic converter The purpose of exhaust cleaning is to reduce the harmful constituents of the exhaust, carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxide (NOx) to a statutory minimum. CO, HC and NOx together make up about 1 - 2 % of the total exhaust quantity. In vehicles with a diesel engine, the oxidation catalytic converter is used for this purpose.

4 - Catalytic converter and DPF with sensors in M67D44O1 engine

18

The catalytic converter can reduce the exhaust components CO, HC and NOx. The oxidation catalytic converter is encased in a stainless steel housing and is firmly embedded in a damping mat. Index

Explanation

1

Exhaust gas back-pressure connection

2

Oxygen sensor

3


4


5

Oxidation catalytic converter

6

Diesel particle filter

The catalytic converter consists of three main components: • Ceramic substrate • Intermediate layer • Catalytically active layer The ceramic substrate is made up of thousands of tiny channels through which the exhaust flows.

6 - Design of catalytic converter

5 - Ceramic substrate

Those channels are covered in an extremely porous intermediate layer. It has the effect of substantially increasing the surface area. The intermediate layer carries the catalytically active layer. The catalytically active layer consists of platinum (Pt) and palladium (Pd).

Index

Explanation

1

Ceramic substrate

2

Intermediate layer

3

Catalytically active layer

The name, oxidizing catalytic converter, means that a conversion takes place in the presence of oxygen. The catalytically active layer makes those conversions possible. The exhaust constituents remain for only a very short time inside the catalytic converter. But that time is long enough for the harmful exhaust constituents to react with the surface of the channels, the catalytically active layer.

22. Note down how the constituent elements of the exhaustgas are converted in the oxidizing catalytic converter.

19

Diesel particle filter The diesel particle filter is encased in a stainless steel housing and is firmly embedded in a damping mat.

the diesel particulate filter. These are closed at their ends. Each inlet duct is surrounded by four exhaust ducts.

The assembly of this diesel particle filter is very similar to that of the oxidation catalytic converter. A so-called monolith (ceramic body) serves as a core. Like the oxidation catalytic converter, the diesel particle filter has many thousand channels running through it, through which the exhaust flows. The difference, however, is that the walls are porous and allow gaseous materials to flow through them. As with the oxidation catalytic converter, the surface is coated with the precious metals platinum and palladium.

7 - E60 diesel particle filter in M57TU2 TOP engine

The coating helps to achieve a reduction in the soot ignition temperature and thus to guarantee good regeneration characteristics of the diesel particulate filter. The exhaust gases flow out of the oxidation catalytic converter and into the inlet ducts of Notes:

20

8 - Cross section of the diesel particulate filter

The soot particles deposit on the coating of the inlet ducts and remain there until they are combusted as a result of an increase in the exhaust temperature. The cleaned exhaust gas flows out of the exhaust ducts through the coated, porous filter walls. The soot particles that are deposited on the filter walls would eventually cause damage to the diesel particulate filter. The soot particles therefore need to be burnt off. This happens when the exhaust temperature rises above the soot ignition temperature. This process is known as filter regeneration. The carbon particles are converted to gaseous carbon dioxide (CO2). If the sulphur content in the diesel fuel is > 50 - 100 ppm, there is a possibility of heavy white smoke development and a sulphur odour from the exhaust tailpipe.

23. Note down how the constituent elements of the exhaustgas are converted in the diesel particulate filter.

24. What is the effect on the diesel particulate filter if solid particles such as oil ash, swarf and additive residues are allowed to enter it?

21

Silencers The purpose of silencers is to reduce the deafening noise of combustion to a comfortable level. Several silencers may be used in combination. They are then

distinguished by their position within the exhaust system, i.e. forward, centre or rear silencer. Frequently, the catalytic converter acts as the forward silencer.

25. Note down the different silencing techniques that can be used in the exhaust system. Technique Absorption

Reflection

Superposition

22

Function

Fuel system Fuel supply system Diesel fuel The engine generates the force to propel the vehicle from the energy stored in the fuel. Diesel alone is the fuel most commonly used for operating diesel engines in passenger vehicles. Diesel is made up of a mixture of various hydrocarbons (HC). Since diesel fuel deposits paraffin crystals at low temperatures, this may cause obstructions in the fuel filter. In unfavourable

situations, paraffin separation may begin from approximately 0 ° C. For this reason, diesel fuels are specially prepared for winter use and provided with flow improvers. This makes winter-grade diesel fuel cold-resistant to temperatures of at least -22 ° C. Mixing gasoline is no longer permissible in modern engines, since this may damage the fuel system. Gasoline has very low cetane numbers, which significantly downrates ignitability.

26. What does the cetane number of a diesel fuel indicate? 4

Power density

4

Boiling point

4

Viscosity

4

Knock resistance

4

Ignitability

4

Density

4

Sulphur content.

27. On the vehicle and dismantled engine, trace the route of the fuel from the fuel tank to the injectors. In the relevant order, note down the components through which the fuel flows.

23

Fuel tank The fuel tanks in modern vehicles are made of plastic. Plastic tanks have the advantage of being lighter, easier to manufacture in the required shape and very safe in the event of an accident.

The fuel tank is shaped to fit the bodywork so as to save space. For safety reasons, it is placed forward of the rear axle. This makes the risk of rupture in an accident relatively low. To a large extent, the fuel tank contains the fuel supply system.

28. Note down the various tasks of the fuel tank.

Notes:

24

9 - E70 fuel tank with diesel engine

Index

Explanation

Index

Explanation

A

Fuel cap

1

Initial fill valve

B

Pressure relief valve

2

Filter screen

C

Non-return valve

3

Fuel pump

D

Surge chamber

4


E

Fuel tank

5

Non-return valve

F

Service cap

6

Feed line

G

Lever-type sensor

7

Return line

H

Filler breather valve

8

Non-return valve

I

Connection

9

Suction jet pump

J

Maximum fill level

10

Run-out protection valve

K

Non-return valve

11

Suction jet pump

L

Filter

12

Pressure limiting valve

29. Which components are responsible for tank venting?

25

30. Explain the tasks of the following components: Component Initial fill valve

Suction jet pump

Pressure limiting valve

Run-out protection valve

Non-return valve


26

Task

Surge chamber Inside the surge chamber is the electric fuel pump (EKP) and a venturi pump. The surge chamber is open at the top. It makes sure that the fuel pump is always immersed in fuel and thus does not draw in any air. Especially when

the tank is close to empty or when the vehicle motion is causing the fuel to move around a lot inside the tank, the surge chamber ensures there are no air bubbles in the fuel delivered by the pump.


Index Explanation

Index Explanation

Initial fill valve

Suction jet pump

Surge chamber

Fuel return

Pressure limiting valve Notes:

27

32. Makes notes about the various components in the surge chamber.

28

Initial fill valve

Notes

Suction jet pump

Notes


Notes

Fuel conditioning system The fuel conditioning system is the system that delivers and meters the correct amount of fuel for combustion. The tasks include: • Supplying the required pressure • Injecting the required volume of fuel (injection-rate control) • Adjusting the required injection start (injection start control).

In order to comply with the stricter emission limits for diesel engines, modern fuel injection systems use more precise injectionand higher pressures. The Common Rail System perfectly fulfils these requirements. With the Common Rail System, the fuel in the rail is stored at high pressure and injected into the combustion chambers in a map-controlled manner.

Notes:

29


Index

Explanation

Index

Rail-pressure sensor

High-pressure pump

Fuel return

Fuel feed from the fuel tank

Leakage oil line

High-pressure line from the highpressure pump to the rail

Rail-pressure regulating valve

Solenoid valve injector

Fuel return to the tank

Fuel feed (low pressure)

Rail (high-pressure accumulator)

High-pressure line from the rail to the injector

Fuel pressure temperature sensor

Fuel high pressure

Volume control valve 34. Explain the tasks of the following components:

30

Explanation

Component

Task

High-pressure pump

Volume control valve

Rail



Fuel injector

31

Fuel injector The injectors are high-precision components that are able to inject the finest and precisely defined fuel volumes into the combustion chamber at precisely determined times. Different injectors are used for the upper and lower power class. The lower power class uses the solenoid valve injectors that have been used since BMW introduced the

common rail system. The upper power class is equipped with the piezo injectors that have been used in the M67TU/M57TU2 since 2005. Thenozzle needles areopened hydraulically in both types of injector. The piezo injector differs from the solenoid valve injector by how the switch valve that controls the hydraulics in the injector is activated.

35. Remove an injector from the dismantled engine. Proceed in accordance with the Repair Instructions.

Notes:

32

Solenoid valve injector

Index

Explanation

8

Supply duct to the nozzle

9

Nozzle needle

10

Control chamber

11

Valve ball

Notes:

10 - Sectional view of the solenoid valve injector

Index

Explanation

1

Fuel return

2

Electrical connection

3

High-pressure connection

4

Coil

5

Outlet restrictor

6

Inlet restrictor

7

Valve control piston

33

Piezo injector

11 - Sectional view of the piezo injector

34

Index

Explanation

Index

Explanation

1

Control chamber

5

Actor module

2

Piezo element

6

Coupler module

3

High-pressure supply

7

Switch valve

4

Fuel feed

8

Nozzle needle

12 - Piezo injector closed

13 - Piezo injector, injection start

Index

Explanation

Notes:

1

Coupler module

2

Control valve

3

Bypass

4

Nozzle needle

5

Restrictor

6

Control volume

7

Outlet

8

Fuel feed

35

Notes:

14 - Piezo injector, injection end

36. What is different about the fuel return line in an engine with piezo injectors by comparison with an engine with solenoid valve injectors?

Notes:

36

Engine electrics 37. Affix to the vehicle or dismantled engine sticky dots with numbers corresponding to the following graphic. If you cannot reach a component directly, affix the dot as close as possible to it. Refer to the BMW diagnostic system if you need assistance.

Index

Explanation

Index

Explanation

1

Digital Diesel Electronics (DDE)

12


2

Accelerator pedal module

13

Exhaust back pressure sensor

3

Crankshaft sensor

14

DDE main relay

4


15

Fuel filter heater

5

Coolant temperature sensor

16

Actuator for exhaust turbocharger

6

Intake air temperature sensor

17

EPPC exhaust gas recirculation (EGR)

7


18

Electric change-over valve for swirl flaps

8

Oxygen sensor

19


9

Camshaft sensor

20


10

Hot-film air mass meter

21

Fuel injectors

11

Throttle valve

22

Preheater control unit 37

Sensors 38. Remove the sensors listed below from the dismantled engine. Using the BMW diagnostic system, determine the functions of these sensors and note down these functions on the worksheet. Then refit the sensors. Component Accelerator pedal module

Crankshaft sensor


Coolant temperature sensor

Intake air temperature sensor

38

Function

Component

Function


Oxygen sensor

Camshaft sensor

Hot-film air mass meter (HFM)

Intake-manifold pressure sensor

Throttle valve sensor

39

Notes:

40

Actuators 39. Remove the actuators listed below from the dismantled engine. Using the BMW diagnostic system, determine the functions of these actuators and note down these functions on the worksheet. Then refit the actuators. Component

Function

Throttle valve

Electropneumatic pressure converter (EPDW)

Electric change-over valve


Preheater control unit

41

Diagnostics Lighting of the emissions warning lamp 40. The emissions warning lamp lights up, but no faults can be detected on the vehicle. Carry out diagnostics on the vehicle and find the cause. In the process, note down: • Each stage of your procedure • The fault description in the fault code memory • The individual stages in the test module • The cause behind the emissions warning lamp lighting up. Summarize your procedure on a flipchart. Solution:

42

Vehicle cannot be started 41. The vehicle cannot be started. Faults relating to the fuel supply are stored in the fault code memory. In the process, note down: • Each stage of your procedure • The fault description in the fault code memory • The individual stages in the test module • The cause behind the emissions warning lamp lighting up. Summarize your procedure on a flipchart. Solution:

43

Vehicle cannot be started 42. The vehicle intermittently fails to start. Various faults are stored. In the process, note down: • Each stage of your procedure • The fault description in the fault code memory • The individual stages in the test module • The cause behind the emissions warning lamp lighting up. Summarize your procedure on a flipchart. Solution:

44

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