Why oxygen sensor error whenever there is rain?
 

Occasionally, one of my O2 sensor will error whenever there is rain, even if I parked my car overnight, the next morning the check light and slip light will light up. approximately 2 dry days later, the warning lights will reset and everything is back to nornal.

I have checked the wire conditions by the mechanic, patched a portion where rats had chewed the insulation but had not resulted a short circuit. But it still happened now.

Why is it after or during raining, what is the logic even if my car is not moving and the sensors are actually beneath and well sheltered.

Before I really spent $90 bucks for the sensor change, I need some member's suggestions.

TIA.