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A method to test the coils of the Volkswagen Polo.

Model: Volkswagen Polo MK IV, Polo 4, 9N, MK 4, Polo IV - Years: 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
Part: Ignition coil

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Video tutorial

In this video, we see a basic functionality test to see if the coil generates a spark; very useful for identifying a faulty coil. In addition to the coil to be tested, we need a test spark plug, a 12-volt power source, cables with alligator clips, and a ground cable.

The coil typically has 3 or 4 pins in the electrical connector. Pin 1 is the control signal that comes from the ECU: it tells the coil when to spark; pin 2 is the ground; pins 3/4 are the power supply (usually connected to the ignition key in the ON position).

We connect a cable from the positive clip to the power pin; a cable from the negative clip to the ground pin; we connect the spark plug; we place the metal body of the spark plug on an engine ground (a clean bolt), and simulate the signal from the control unit, taking a cable and connecting it to the coil signal pin. It would be good to use a momentary button between the signal pin and the ground (like a start button).

If the coil is good, we will see a strong blue spark on the spark plug every time we send the signal.

If the coil is faulty, there will be no spark or it will be reddish and intermittent.


Posted on 8 September 2025 by ScegliAuto


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