Ignition coils produce a high-voltage current that fires the spark plugs. If a coil fails, like in the case of many VW engines, the spark plug won’t fire and the engine will lose power.
The National Highway Traffic Safety Administration has opened a preliminary evaluation on failing ignition coils in Volkswagen engines. According to the Wheels Blog at NY Times, the investigation is focusing on almost 200,000 2002-2003 VW Passats, depending on the results this could open into a full-sledged defect investigation:
“The agency says the investigation is looking at an estimated 199,000 Passats from the 2002-3 model years after receiving 16 reports that faulty ignition coils caused either fires or a loss of power on 4- and 6-cylinder engines.”
In 2003, Volkswagen had a serious problem with ignition coils on many of its most popular models.