Sensor Change Warning On ToxCO

Why does my ToxCO have an orange circle with 'SEN01' and a date in orange below it?

ToxCO-sensorThe device's sensor change is due in 60 days or less, contact your distributor to arrange a service.

If the problem persists or has not been resolved by the information provided above, please contact Bedfont or your local distributor for more advice.