The life span of the valve cap is entirely dependent of the battery shelf life, which is 3-4 years of standby time. The cap can flash continuously for approximately 3 weeks. Like with all warning devices, it is strongly recommended that the valve cap is checked periodically to ensure that it is working properly. It is also recommended that it is replaced, along with the valve stem, when replacing your tires, or at least every 3-4 years.