Rep Power: 958

I'm trying to see if one of my O2 sensors is bad. My car has a OBD1 ECU so I'm not sure if it will throw an SES light if one of my O2's is bad. My car has been running real rich and blows black smoke out the exhaust (more than normal) every now and then under WOT conditions. Is their anyway to check for a bad O2 sensor?

Thanks

 
Rep Power: 1125

hook up a scan tool start the engine if the sensor is bad it won't go from closed to open loop, and a bad o2 sensor will throw a code (the scan tool should have a reference on how many flashes is closed loop and how many is open)

 
Rep Power: 958

Will a scan master be able to detect O2 sensor voltage?

 
Rep Power: 1125

should be able to