honda safety belt sensor problem will cause the airbag light on if you unbuckle while the engine is on, an easy way to confirm if it is this problem is to buy a seat belt extender and buckle it into the original buckle, unbuckle the seat belt with the engine on and the seat belt extender inside, if no airbag light is on, then it is for sure the sensor is bad. Then you can go to the dealer to show them the test and ask for a free fix.
you can buy it online ebay for $7.99
