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

 

Sounds like O2's to me. I would just replace both of them if I were you. You may even see a increase in gas mileage. My car did the same thing at about 100k o2's fixed it. You can check your o2's with scanning software like datamaster if you have a ALDL cable. I think normal readings are around .400mV-.600mV (I think thats what its measured in). Hope that helps