yes they test it but the only visual check is the warning light…….if the system is working properly it should come off after a few seconds and if you are extremely lucky they might not notice the situation if you remove the bulb.
If the warning light is on you will have to repair it and return to the station again.
I can sell you a new sensor for approx 900kr but do remove the wheel and disc and check for dirt around the sensor. They are very sensitive and especially if the sensor ring is placed visible so it can rust. Do not remember how it is made on 900OG but I can imagine that the sensor ring is a one piece item with the hub.
You can test the sensor if you have an AC/DC /Ohm meter. It should read 20-40 Ohm in resistance and if measured in AC voltage it should read some volts when spinning the wheel.