How to clear 02 sensor Fault

[benda515]

I have a 2012 Mercruiser Mag 350 and added the vessel view mobile to identify a warning horn that would sound every couple minutes. The app told me it was 02 sensor back one on the port side of the starboard engine. I replaced it but the fault is still there. Is there anything I can do to reset the fault. I dont believe it is showing the error from an actual problem as it shows the error even when I turn the key to start with out firing up the engine. Any help would be greatly appreciated. Runs great but I hate the beep every minute