Can a key that has been used 100% of the time go bad and cause the theft deterant mode to switch on causing the engine to cut off after being started then when it finally stays running the airbag light stays on? Dealer first said the airbag connection was lose and charged me $170 to fix it. Then when airbag light came on again, cleared the light and told me my key was bad and to use other key. Is this plausible?