DAF LF45, LF55 Series. Manual - part 158

©

 200505

2-1

BE/CE engine, general

DIAGNOSTICS

ΛΦ45/55 series

2

1

2. BE/CE ENGINE, GENERAL

2.1 INTRODUCTION

If there is a fault in the system, it is usually 

detected by the electronic unit in the form of a 

fault code. This fault code can be read out using 

DAVIE. The fault-finding table contains possible 

causes of symptoms not detected by the 

electronic unit. 

DIAGNOSTICS

2-2

©

 200505

BE/CE engine, general

1

ΛΦ45/55 series

2

2.2 FAULT-FINDING TABLE, ENGINE FUNCTIONS

SYMPTOM: ENGINE CAN BE STARTED, BUT DOES NOT RUN

Possible cause

Remedy

Poor fuel quality

Drain fuel, flush fuel system, replace the fuel filters 

and fill fuel tank with fuel

Air in fuel system

Check for drawing in of air:

-

via the suction pipe

-

via the fuel lift pump seal

Fuel filter clogged

Replace the fuel filter and clean the system

While carrying out an engine test with DAVIE, 

communication with DAVIE was interrupted

Remove the battery earth lead and then refit it

No fuel supply/fuel lift pump defective; no delivery Check:

-

the fuel level

-

the pipes for blockage and leaks

-

the fuel lift pump

SYMPTOM: ENGINE STALLS AND RUNS AGAIN AFTER RE-STARTING

Possible cause

Remedy

Air in fuel system

Check for drawing in of air:

-

via the suction pipe

-

via the fuel lift pump seal

SYMPTOM: ENGINE STARTS POORLY

Possible cause

Remedy

Poor fuel quality

Drain fuel, flush fuel system, replace the fuel filters 

and fill fuel tank with fuel

Air in fuel system

Check for drawing in of air:

-

via the suction pipe

-

via the fuel lift pump seal

Fuel filter clogged

Replace the fuel filter and clean the system

Battery voltage too low

Charge the batteries

Mechanical defect or clogging in injector

Replace the injector

Fuel lift pump delivery too low

Check the fuel lift pump and replace if necessary

Internal leakage between the fuel supply pipe and 

the injector

Check the fuel supply pipe/injector connections for 

internal leaks

©

 200505

2-3

BE/CE engine, general

DIAGNOSTICS

ΛΦ45/55 series

2

1

SYMPTOM: ENGINE RUNS AT (INCREASED) IDLING SPEED AND DOES NOT RESPOND TO 

ACCELERATOR PEDAL

Possible cause

Remedy

Mechanical defect of accelerator pedal sensor

Check:

-

the mechanical connection between the 

sensor and the accelerator pedal

-

the accelerator pedal sensor

Fuel quantity adjustment by ABS/ASR

Engine brake input signal present

Check the electrical system of the engine brake

SYMPTOM: DIESEL KNOCK DURING ACCELERATION

Possible cause

Remedy

Poor fuel quality

Drain fuel, flush fuel system, replace the fuel filters 

and fill fuel tank with fuel

Air in fuel system

Check for drawing in of air:

-

via the suction pipe

-

via the fuel lift pump seal

Injector defective

Inspect the injectors

SYMPTOM: IRREGULAR RUNNING OF ENGINE

Possible cause

Remedy

Poor fuel quality

Drain fuel, flush fuel system, replace the fuel filters 

and fill fuel tank with fuel

Air in fuel system

Check for drawing in of air:

-

via the suction pipe

-

via the fuel lift pump seal

Fuel filter clogged

Replace the fuel filter

Connection points on injectors mixed up

Connect the correct connection points to the 

correct injector

Mechanical defect or clogging in injectors

Replace the injectors

Injector defective

Inspect the injectors

Fuel lift pump delivery too low

Check the fuel lift pump and replace if necessary

Pressure relief valve on fuel rail does not shut off

Check the pressure relief valve

DIAGNOSTICS

2-4

©

 200505

BE/CE engine, general

1

ΛΦ45/55 series

2

SYMPTOM: REDUCED POWER AT ALL ENGINE SPEEDS

Possible cause

Remedy

Poor fuel quality

Drain fuel, flush fuel system, replace the fuel filters 

and fill fuel tank with fuel

Fuel filter clogged

Replace the fuel filter

Mechanical defect of accelerator pedal sensor

Check:

-

the mechanical connection between the 

sensor and the accelerator pedal

-

the accelerator pedal sensor

Fault in electrical components/wiring of:

-

contacts

-

contact resistors in connector contacts

Check the electrical system

Air filter clogged

Replace or clean the air filter

Turbocharger defective/wastegate control 

incorrect

Check the turbocharger/wastegate control

Air leak in inlet system

Pressure-test the inlet system

Mechanical defect or clogging in injectors

Replace the injectors

Fuel lift pump delivery too low

Check the fuel lift pump and replace if necessary

SYMPTOM: REDUCED POWER ABOVE A CERTAIN ENGINE SPEED

Possible cause

Remedy

Fuel filter partially clogged

Replace the fuel filter

Air filter partially clogged.

Replace or clean the air filter

Air leak in inlet system

Pressure-test the inlet system

Fuel lift pump delivery too low

Check the fuel lift pump and replace if necessary

SYMPTOM: WHITE/BLUE SMOKE IS EMITTED

Possible cause

Remedy

Poor fuel quality

Drain fuel, flush fuel system, replace the fuel filters 

and fill fuel tank with fuel

Air in fuel system

Check for drawing in of air:

-

via the suction pipe

-

via the fuel lift pump seal

Fuel filter clogged

Replace the fuel filter and clean the system

Mechanical defect or clogging in injectors

Replace the injectors

Injector defective

Inspect the injectors

Fuel lift pump delivery too low

Check the fuel lift pump and replace if necessary