Main faults of the engine management system (VW Golf 4)

Before troubleshooting, make sure that there is sufficient fuel in the fuel tank, the engine has no mechanical defects, the battery is charged and the starter turns the engine crankshaft at a sufficient speed, the ignition system is in good condition, the fuel system is sealed and free of contamination, the crankcase ventilation hose is clean and the powertrain ground bus is securely connected.

Pre-check the faults recorded in the engine management system memory.

CAUSE	METHOD OF ELIMINATION
Difficulty starting the engine or the engine does not start at all
The diesel engine preheating system does not work	Check and, if necessary, restore the functionality of the diesel engine preheating system
The fuel shut-off valve does not open	Check the fuel shut-off valve of the engine control unit and the anti-theft system
Defect in the fuel supply system	Check the fuel supply system to the engine
Fuel supply lines are leaky, blocked internally or deformed	Clean and, if necessary, replace fuel supply lines
The fuel filter is dirty	Replace the fuel filter
In winter, there is water or ice in the fuel filter	Warm up the car in a heated garage
The fuel tank ventilation is clogged or the fuel filter located in the fuel tank is dirty	Clean the fuel tank ventilation system or fuel filter
Fuel injection timing is incorrectly adjusted	Check and adjust fuel injection timing if necessary
The fuel injectors are faulty	Check the functionality of the fuel injectors
The high pressure fuel pump is faulty	Replace the high pressure fuel pump
The engine only runs at idle speed
The fuel hoses on the high pressure fuel pump or on the fuel filter are loose	Secure the fuel hoses properly
The fuel supply and return hoses on the high pressure fuel pump are not connected correctly	Check that the fuel hoses are connected correctly
Increased fuel consumption
The fuel filter is dirty	Replace the fuel filter
The fuel system is leaking	Check and, if necessary, restore the tightness of the fuel system
The fuel return line is dirty	Clean the fuel return line