Question Strange behavior of O2 sensor

[Cio]

If you replaced the cell, then the harness, and it acted the same, the electronics are suspect. You can have issues with the internals of those same as wiring.

I doubt you have it but if you can generate mV, you can set it up @ 100mV hard wired, and dig in.

 

[Vevera]

I experienced similar behavior of sensor #1 and sometimes #2 when diving in very humid climate (or when I was too lazy to open my unit overnight after a short dive). It always occured at the beginning of the dive and disappeared by itself after a minute or two.

I assume it was caused by a droplet of water falling on the sensor which was dryed out soon by the gas flow. It never occured in dry areas once I started paying more attention to drying my unit after diving. Using aircon in humid areas when drying my unit helped as well.