Today I got around to chacnging my O2 sensor. I didn't rush because since I bought the car in July I've found that everything I've replaced was almost new.

However, when I took off the sensor today, it didn't look new, and another surprise, the body of the sensor was cracked in several places.

Is this from age, or is there another factor in play?

On my 88 V6 bird and my mother's 89 Grand Am, as old as the sensors appeared I had never seen them cracked.

 

Excessive heat or sudden temp change might explain it.
Water splashed on it when it's hot and operational might do it.
Maybe over torqued at installation.

Just guessing.