Nissan Repair: 1997 Maxima Oxygen Sensor Code issues, nissan maxima, o2 sensors

Question
I have a 97 Nissan Maxima with 90,000 miles on it, but over the last few months I have had a problem with the O2 sensors.  I have replaced the O2 Sensors and the Knock Sensor because the Codes keep coming up when the check engine light is on.  The check engine light is back on and the code is now a o2 circuit malfunction...Could this be caused by the coils as well?  I noticed that was suggested on a 98 Maxima..

Answer
Richard,

Yes, if the coils are not firing properly it could cause too much gas in the exhaust.  Also, have the injectors checked to see if any are leaking as too much fuel can cause the problem.  EMail me the exact code and let me know what it is.  If the heater circuit is defective it could be the relay that runs the heated circuit.