U.S. safety regulators are investigating whether a recall to fix air bags on nearly 745,000 Chrysler SUVs is working properly.

The company recalled older-model Jeep Grand Cherokees and Libertys in 2012 because the air bags could inflate without a crash, causing injuries.

Chrysler installed an electrical filter to eliminate electrical spikes on air bag circuits and thought that would solve the problem.

But since the recall, the company has received six reports of air bags inflating without a crash on SUVs that had the recall repairs.

No crashes were reported, but owners said there were some cuts and burns, according to documents posted Monday on the National Highway Traffic Safety Administration website.

The safety agency says it’s investigating whether the recall is working. Chrysler says it’s cooperating but hasn’t determined whether the recall is working.

The investigation affects Libertys from the 2002 and 2003 model years and Grand Cherokees from 2002 to 2004.

The company says customers with concerns can call (800) 853-1403.