Nissan Repair: Service engine soon, oxygen sensors, oxygen sensor

Question
I have a 2003 Maxima which has done about 39000 miles. Recently I have done a lot of long distance driving and the Service Engine Soon light came on. I had Diagnostics done at the local AutoZone which came up with error codes P0037( oxygen sensor failure) and P1615 (Anti theft system failure). Is it possible for the Factory installed Anti theft system to just fail like that. The oxygen sensor failure,is it common. Should I be taking the car to Nissan Dealership( they are a ripp off) or outside mechanics can handle these kind of problems with expertise. Do I need to rush into getting these repairs. The car itself is running fine. Thank you very much.

Answer
Gaurav,

First, I would purchase all three oxygen sensors.  I personally have a 2000 Maxima SE and my oxygen sensors finally failed too.  I did the cheapie one at a time route and ended up doing all three within a month.  So, just get over with it and do all of them.  They get coated at about the same rate so just do it.  courtesynissan.com is a good alternative to a dealer and anyone with a oxygen sensor socket can do the work.  You will just need to get the car on a lift to access them.  They are like oversized sparkplugs with long wires that lead to connectors.  Armorall the connectors first to get them to loosen up for being unpluged and spray WD-40 on the old sensors to aid in their removal.  For the alarm code I would try resetting the computer by disconnecting the battery.  If it comes back it is usually the body control module.  Source a used one since a new one is over $300 bucks for the part.  I would replace the oxygen sensors soon since they can cause the converters to melt if you drive it too long with them reading wrong.  Basically, they get coated with fuel additives and they read lean and too much gas will cause the converters to melt and block the exhaust flow.  A big plus is your car is going to run great once they are replaced.