o2 sensor grounded to thermostat housing?

[levimits]

Why is this o2 sensor wire grounded to the thermostat housing? And is this whats causing my car to run rich in closed loop?

 

[FIBA M - EC17PSE]

It could be your reason! My ecu blew and I asked if I could ground the yellow wire aswell but it has to be seen by the ecu to function the sensors properly, they might have done it as a cheap fix as the ground pin 60 on the ecu is a ground but is internal and if it did stop working this could have been an easy fix for them this only leads me to think the ecu is broken only because I had the same idea