Recalls of some 800,000 cars in the last year to address issues with so-called smart air bags and occupant-detection systems are raising questions about the products' IQ. The new, smarter front-passenger air bags were first installed in 2004 models to prevent injuries and deaths in young children and small women from bags that deployed at a force meant to protect an unbelted, 165-pound man. But the bags may not always deploy when they should—or may when they should not. The smart systems, in all passenger vehicles starting with 2007 models, are designed to tell the front air bag whether to deploy, and in some systems how forcefully to deploy, based on the weight of the passenger. To determine that, some systems use bladders filled with gel; others use a mat in the seat. Both are geared to tell the air bag controller not to deploy when the passenger weighs less than 105 pounds.
For a number of reasons, however, that's not always happening. A 2007 BMW recall of 200,000 vehicles, for example, found that small cracks could develop in the sensor mat and keep the bag from deploying. Hyundai recalled almost 394,000 Sonatas because the sensors might mistake a small adult for a child, similarly stopping deployment. Nissan recalled more than 200,000 vehicles because of a faulty sensor in the seat cushion that also would stop deployment. BMW says its recall was not an admission of a safety defect. "In this case, there would be two lights on in the car that would warn the customer that there is something wrong with the air bag system," said Thomas Plucinsky, product and technical communications manager for BMW of North America LLC.
But Sean Kane, president of Safety Research & Strategies Inc., contends that "systems are being tricked and fooled." Hyundai and Nissan agree that this is a safety issue. Chris Caruso, an engineer who spent 20 years designing automotive air bag systems, cites the complexity of the technology, with challenges ranging from environmental extremes to normal wear and tear. Temperatures, for example, can change the way gel flows. A leather seat can read weight differently when it's hot than when it's cold, Caruso said. Over time, foam in the seat can break down or shift. But safeguards are in place. One is the warning light on the dashboard, which is designed to illuminate when something's wrong with the system, Caruso said.