Testing O2 Sensor/Cat

[Threehz]

Is there any way to test a cat or O2 sensor besides replacing them?

[89 e30]

You can test the cat by testing back pressure and o2 you can test like this http://www.ehow.com/how_4855734_test-sensors.html

[LJ851]

Unfortunately i do not know the specifics, but you can test a cat by the temp of the air entering and exiting with a heat gun (sensor). I want to say it should climb 100 degrees but don't quote me.