Thousands of US motorists are driving around with potentially lethal counterfeit air bags fitted to their cars.
Road safety watchdogs are warning all those whose air bags have been replaced in the past three years may be affected.
The National Highway Traffic Safety Administration alerted the industry that tens of thousands of cars could be involved.
NHTSA testing has shown some of the counterfeit bags, believed to have been made in China, do not inflate or fail to inflate properly. In at least one case, a counterfeit bag fired shards of plastic and other projectiles on impact,
Car owners are being told to check a government website or call their manufacturer or local dealer to see if their vehicle model is affected.
No deaths or injuries have been tied to the counterfeit bags, but it is unclear whether police accident investigators would be able to identify a counterfeit bag from a genuine one.
The agency has compiled a draft list of dozens of vehicle makes and models for which counterfeit air bags may be available. NHTSA cautions at the top of the draft that the agency "expects this list to evolve over time."
If the car is on the list and has had its air bags replaced during the past three years by a garage other than a new car dealer, owners will be asked to take the vehicle into a main dealer to check if the bags are counterfeit.
The counterfeit bags usually include a manufacturer's logo. Government investigators believe many of them come from China.
The bags are marketed to car body shops as the genuine article, officials said. Dealers with their own body shops are usually required by their franchise agreements to buy their parts, including air bags, directly from car makers and therefore are unlikely to have installed counterfeit bags.