If one of the O2 sensors on my car (1996 850 2.4 N/a Base Sedan) has gone bad, would it throw a check engine light? Could it have gone bad and not triggered the light? (Car already had a CEL on for an evap. leak, gas cap seal went bad, had it checked at an auto-zone and that was the only code that came up) My exhaust smells like its running a bit rich and my fuel economy has decreased slightly. Disconnecting and reconnecting the negative battery terminal would reset the CEL computer to see if it's been fixed, correct?
Thanks for any input!
-Luke

 

yes if the O2 sensor goes out of its voltage range it will throw a CEL. Problem is to figure out if the sensor is out of range because of the sensor or because the fuel metering is off - say due to an intake air leak, MAF, fuel pressure regulator etc. Disconnecting the battery won't clear the codes as they are stored in the ECU's memory. Best to get the codes read again and cleared to see if they reset or if new codes are getting set.