WASHINGTON – Car owners whose air bags have been replaced in the past three years may have had dangerous counterfeit bags installed, the Obama administration warned Wednesday.

Only 0.1 percent of the U.S. vehicle fleet is believed to be affected, the National Highway Traffic Safety Administration said in a statement. But industry officials briefed by the government said tens of thousands of car owners may be driving vehicles with counterfeit air bags. NHTSA testing has shown most of the counterfeit bags don't inflate or fail to inflate properly. In at least one case, a counterfeit bag fired shards of metal shrapnel on impact, the agency said.

NHTSA is asking car owners to check a government website, www.Safercar.gov, for information on how to contact a call center established by auto manufacturers to learn if their vehicle model is among those for which counterfeit air bags are known to have been made.