The probe covers about 630,000 Wranglers from the 2007 through 2012 model years.
The National Highway Traffic Safety Administration says it has 221 complaints that the air bag warning light is illuminating, indicating an electrical problem in the steering wheel. Jeep maker Fiat Chrysler recalled some right-hand-drive Wranglers in 2011 for the same problem. Now the agency is looking at left-hand-drive vehicles.
The agency reports no crashes or injuries because of the problem. The investigation could lead to another recall.
Fiat Chrysler says it is co-operating in the investigation. Owners whose air bag lights come on should contact their dealer.