If the COA-26 indicates END, it means that the sensor is at the end of its lifespan. 

The CO Alarm must be replaced to ensure your continued safety. 

We recommend purchasing a CO Alarm directly from us for the best support. 

You can purchase a new carbon monoxide detector via the following link: Alecto carbon monoxide detectors

If you would like some advice, we can always help you with that. You can send us a message by clicking on 'contact us'.