Identifying and troubleshooting engine faults (Mercedes-Benz A-Class W168)

If the engine does not start, then gradually narrow the search for the fault. For the engine to start, two basic conditions must be met: the fuel-air mixture must enter the cylinders, and there must be an ignition spark on the spark plugs. Therefore, first of all, you should check whether there is a fuel supply. How to act in this case is indicated in the sections "Fuel system" and "Ignition system".

Malfunctions of electronic control units can only be detected and eliminated using special control and measuring devices. When checking spark formation, observe the precautions specified in the relevant chapter.

For diesel engines, check the preheater and fuel system.

The engine starts poorly or does not start at all

The fuse is faulty:

• fuel pump with electric drive;
• electronic injection system;
• preheating systems.

Check the fuse.

Ignition system malfunction

Have the ignition system checked by a workshop.

The engine control unit is faulty

Have the engine control unit checked at a workshop.

Faulty, contaminated fuel system

Check the fuel pump and lines.

The starter turns too slowly

Charge the battery. Check the power supply to the starter. Clean the contacts.

[Original material on the website: MercedesMan]

The anti-theft system does not turn off

Use the spare ignition key. Check the anti-theft system.

Defective cylinder head gasket

Replace the gasket.