The probe covers about 363,000 of the popular midsize cars from the 2008 model year.
The National Highway Traffic Safety Administration says 28 drivers have complained about the problem. Two people reported injuries.
Investigators will determine how often the problem happens and whether a recall is needed.
Honda says in a statement that it will cooperate with NHTSA on the probe and will continue its own review.
In many of the complaints, owners reported having to pay thousands of dollars to fix the problem. One owner reported in July that the side air bags inflated when his son closed the passenger door, causing a scrape on his right forearm. "This is clearly a safety issue," the owner said in the complaint.