Diagnostics of diesel engine faults (Mercedes-Benz C-Class W202)

If the engine does not start, then it is necessary to localize the malfunction. A number of conditions must be met for the engine to rotate: no errors in driving the car; fuel tank filled with fuel; normally working starter.

CAUSE		REMEDY
The engine starts poorly or does not start at all
Control errors at startup	Starting a cold engine	Turn on the ignition until the indicator lamp goes out. Immediately after the indicator lamp goes out, start the engine.
	Starting the engine warmed up to operating temperature	No preheating is required, the engine starts immediately.
Preheating device does not work	Preheating indicator light does not light	Check the indicator lamp, glow plugs and preheat relay.
	The pre-heating lamp is on	Turn ignition off. Disconnect 2 glow plug wires for cylinders 2-4, turn ignition on; if the indicator light is on, check the preheating relay and replace if necessary.
The fuel system is faulty	No fuel supplied	Fuel lines (suction, recirculation, injection hoses) kinked, clogged, leaky. The fuel filter is clogged.
	The moment of the beginning of fuel access has been shifted	Check the moment the fuel starts to flow and adjust it.
	The injector is faulty	Check the injectors
The fuel pump is faulty	All cylinders fire simultaneously	Replace the fuel pump.
The starter turns too slowly		Charge the battery. Check the starter electrical circuit.
Compression too low		Repair the engine.
The cylinder head gasket is faulty		Replace the gasket.