Why does my GastroCH4ECK say 'SEN01' and a date in red?

Sensor Change Is Overdue On GastroCH4ECK

Your device's sensor change and service is overdue. Make arrangements to service the device. See the user manual for more information regarding the service of device. 

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