I had exactly the same with mine. Mentioned it to the dealer when in for a service. They identified an over-sensitive sensor and since that was changed, it's never (tempting fate there, I know ) happened again. Worth a try!My alarm on the 159 keeps going off, usually due to a chav type with a big bore exhaust going by. Is there anythng I can do? Can it be adjsuted? Do the vents make any difference?