Oh, I missed the part where you already tried to replace the sensor. Cool, backups to backups.
I have an old IC in its box, in my garage. It can still make chlorine, but lost some of the comms to my EasyTouch (another known issue). Pentair replaced it, by mail, but never asked for the old one back (which is how I know its a known issue). So I've been using the new one, and will switch back to the old one when the new one nears end-of-life. But I'll try to catch it before it's completely dead, so that the new one will go into the box and become the backup for the old one.
And then repeat all that with the third one some day, so that I'll always have two on site. The newest online, using up it's warranty, and the previous one with just enough juice left to work as a back up should the "primary" ever fail. The backup stepping in while I await a replacement. Followin' all that?!
Musical SWGs! That's how much I don't want to be without my SWG!!!
I just have to remember to do the cell-life test every so often, so I know when to switch 'em out (I made a calendar reminder for that).