Ignition Coil Problem Identified on VW Passats

The National Highway Traffic Safety Administration has intensified its investigation into possible fire problems on nearly 500,000 Volkswagen Passats with 4-cylinder turbo engines.

According to a document filed Sunday on the agency's Web site, the investigation covers 490,000 Passats from the 2001-7 model years.

The focus of the investigation involves ignition coils, a trouble spot for the German brand since at least 2003, when the automaker admitted problems with its 2001-2 4-cylinder engines. That population of vehicles appears to be covered in the new investigation.

The coils are used to generate the high-voltage current that fires spark plugs, and VW dedicates one coil for each plug. On the 4-cylinder models being investigated, then, there would be four ignition coils. When a coil fails, the spark plug does not fire and the engine loses power.

Last August, N.H.T.S.A. opened a so-called preliminary evaluation — a low-level inquiry — into an estimated 199,000 Passats from the 2002-3 model years. The primary concern was fires caused by failing ignition coils.

Sunday's N.H.T.S.A. document stated that additional consumer complaints and records provided by Volkswagen indicated sufficient reason for concern to begin a more serious "engineering analysis" and greatly expand the number of vehicles covered. An engineering analysis brings N.H.T.S.A. a step closer to a recall, although sometimes the agency concludes that its concern was not warranted after all, in which case the investigation is simply ended.

The agency said it had received 14 complaints of fires and another 21 complaints of ignition coil failures that caused vehicles to suddenly lose power. Volkswagen reported another 199 complaints, although it was not clear how many of those involved fires.

A Volkswagen spokesman could not be immediately be reached for comment. However, after last August's preliminary-evaluation opening, the automaker said it was cooperating with the safety agency.