WASHINGTON (AP) _ The U.S. government said Friday it was re-examining a 2004 recall of Audi sedans for wiring problems after it received six reports of fires starting in the driver's side dashboard.

In March 2004, Audi recalled about 173,000 models of the A6, S6 and Allroad Quattro vehicles made between 1998 and 2004. But the National Highway Traffic Safety Administration said it has recently received the reports of fires in A6 sedans from the 1998-2004 model years.

It will investigate whether the recall was adequate.

Audi spokesman Patrick Hespen said the automaker had not yet received information about the inquiry but would co-operate with NHTSA in the review.

The government, meanwhile, opened separate investigations on models from Ford Motor Co., Chrysler Corp. and Toyota Motor Corp.

An estimated 700,000 models of Ford Super Duty trucks from the 1999-2001 model years are being investigated following 31 complaints of engine stalling. Owners said the engines stalled without warning and they experienced diminished steering and braking. Three low-speed crashes have been reported and no one was injured.

Ford spokeswoman Kristen Kinley said the automaker was working with NHTSA but it was too early to determine the investigation's outcome.

In the Chrysler investigation, NHTSA said it was reviewing a 2004 recall of about 38,000 Chrysler Pacifica sport utility vehicles because of engine stalling. There have been 60 complaints of similar problems in 2004-2006 vehicles. No crashes or injuries have been reported.

DaimlerChrysler AG spokesman Max Gates said they would work with the agency as the investigation proceeds.

NHTSA is also investigating 2004-2005 model years of the Toyota Sienna minivans equipped with run-flat tires. A dozen owners have complained about the tire pressure warning system, saying the warning light did not warn of low tire pressure.

Run-flat tires, allowing motorists to drive under 88 km/h for up to 160 kilometres without air pressure, are standard on all-wheel drive Sienna models, spokesman Sam Butto said. He said Toyota was co-operating in the investigation.