If the alarm is going off *despite* the seatbelt being buckled, there might be a problem with:
* The seatbelt buckle itself: It could be faulty and not properly registering with the sensor. Try cleaning the buckle and its connection point.
* The seatbelt sensor: This sensor can malfunction and need replacement.
* A wiring issue: A broken or loose wire in the seatbelt system could be causing the problem.
* The Occupant Classification System (OCS): Some vehicles with passenger-side airbags have an OCS that detects the presence and weight of a passenger. If this system is malfunctioning, it might trigger the seatbelt alarm.
If buckling the seatbelt doesn't stop the alarm, you'll need to have a mechanic diagnose the problem. They'll be able to test the buckle, sensor, and wiring to determine the cause.
