what is the voltage output of a good upstream O2 sensor? I have an error code number 43 on my car and wanted to check that also. I think it's the ignition coil but I can't check that until I get the new one tomorrow. Do these need to be changed every so often?

43 may be a multiple cylinder misfire. o2 sensor code is 21 I believe. I changed my o2 sensor, and the a/f gauge shows it fluctuates more now, but it didn't help the idle much at all...