I stopped at a red light in a left lane. A vehicle behind me hit accidentally my car with an awful crash sound. My passenger and I had seat belts on. The air bags did not deploy but after the hit a message appeared on the dashboard related to "SRS airbag system malfunction. Visit your dealer". I want to make sure that the airbags is not defective and would like to understand when should an airbag deploy itself to make sure that I can be safe again in my car.