DAF LF45, LF55 Series. Manual - part 284

©

 200416

2-5

Fuel system

DIAGNOSTICS

ΛΦ45/55 series

4

1

SYMPTOM: FUEL CONSUMPTION TOO HIGH

Possible cause

Remedy

Poor fuel quality

Drain fuel, flush fuel system, replace the fuel filters 

and fill fuel tank with fuel

Fuel fine filter/coarse filter clogged

Replace fuel fine filter and clean the system

Injector(s) mechanically defective or clogged

Replace the injectors

Leak in fuel system

Check for leaks

SYMPTOM: REDUCED MAXIMUM ENGINE SPEED

Possible cause

Remedy

Air in fuel system

Check for drawing in of air:

-

via the suction pipe

Fuel fine filter/coarse filter clogged

Replace the fuel filter and clean the system

Injector(s) mechanically defective or clogged

Replace the injectors

High-pressure pump or fuel lift pump delivery too 

low

Check:

-

the high-pressure pump

-

the fuel lift pump

DIAGNOSTICS

2-6

©

 200416

Fuel system

1

ΛΦ45/55 series

4

©

 200416

3-1

Inlet/exhaust system

DIAGNOSTICS

ΛΦ45/55 series

4

1

3. INLET/EXHAUST SYSTEM

3.1 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

3-2

©

 200416

Inlet/exhaust system

1

ΛΦ45/55 series

4

3.2 FAULT-FINDING TABLE

SYMPTOM: REDUCED POWER AT ALL ENGINE SPEEDS

Possible cause

Remedy

Air filter element blocked

Replace the air filter element

Turbocharger defective/wastegate control incor-

rect

Check the turbocharger/wastegate control

Air leak in inlet system

Pressure-test the inlet system

SYMPTOM: REDUCED POWER ABOVE A CERTAIN ENGINE SPEED

Possible cause

Remedy

Air filter element partially blocked

Check/replace the air filter element

Air leak in inlet system

Pressure-test the inlet system

SYMPTOM: FUEL CONSUMPTION TOO HIGH

Possible cause

Remedy

Turbocharger defective

Check the turbocharger

Air leak in inlet system

Pressure-test the inlet system

SYMPTOM: REDUCED MAXIMUM ENGINE SPEED

Possible cause

Remedy

Turbocharger defective

Check the turbocharger

SYMPTOM: RISING AND FALLING TURBOCHARGER SOUNDS

Possible cause

Remedy

Blocked turbocharger air intake

Check air intake and remove any obstacles

Compressor side of turbocharger contaminated

Clean compressor side with a non-corrosive clean-

ing agent or a soft brush. Check the intake side for 

carbon deposits or other contamination

Turbocharger damaged

Replace the turbocharger and identify the cause

SYMPTOM: BLACK SMOKE EMERGES FROM EXHAUST

Possible cause

Remedy

Air filter element blocked

Replace the air filter element

Air leakage between turbocharger and inlet mani-

fold

Check flexible pipes and pressurise intake unit

Air leakage between the inlet manifold and cylinder 

head

Check for leakage. Replace gaskets, if necessary