Engine fault diagnostics (VW Passat B3)

When the engine does not start, a systematic approach is needed to identify the fault. In general, for the engine to start, 2 basic prerequisites must always be met. The fuel-air mixture must enter the cylinders, and there must be a spark at the spark plugs. Therefore, first of all, it is always necessary to check whether fuel is supplied at all. How to act in this case is described in the chapters "Power supply system" and "Injection system".

To determine whether there is a spark, you need to unscrew the spark plugs, insert them into the tips and individually short-circuit the body of each spark plug to ground. In this case, hold the spark plug tip or high-voltage wire not with your hands, but with a well-insulated clamp. Ask an assistant to start the engine. If a spark does not jump, then the malfunction should be detected in accordance with the recommendations of the chapter "Ignition system".

Caution: Observe safety regulations when working with the electronic ignition system.

Caution: On diesel engines, check the glow plug preheating system.

Malfunction: The engine starts poorly or does not start at all.