[scarceller]

You can in car test any narrow band O2 sensor, here's how:

Disconnect the sensor from the harness so it's not plugged in at all. If the sensor has a signal line and also heater lines then if possible leave the 12vdc heater lines connected but not the signal line. Then with motor fully warm and running at idle measure the voltage at the signal line it should read somewhere in the range of 0.0 to 1.0 volts. Where anything below 0.5 is lean and above 0.5 is rich.

You won't know what side the engine is running at (lean or rich) before hand but if the sensor reads 0vdc it's either bad or very lean, so what you will do next is richen the mixture intentionally. In the CIS cars this is easy, just slightly push up on the air plate in the air meter funnel, this adds fuel to the mixture and the sensor MUST saturate at above 0.7vdc

If the sensor is already reading rich then go the other direction and lean it by pulling down on the air plate slightly and the sensor must drop below .3vdc

In the CIS cars it's very very easy to alter mixture via this air plate method.

If you find that the sensor does not respond to the mixture changes then the sensor is bad. Once you do this method on a properly working sensor you will really get the hang of how it's done via this very easy method.