I want to change the (2)o2 sensors on my 98' (before the cat) as i know the are the original ones. I have looked under the car and it looks like a tight squeeze.

Is there a write up on the procedure?

 

The Maxima is one of the easier 6 cylinder cars where I have changed the O2 sensors. I usually use a 22mm or 7/8 inch open end wrench or an O2 sensor tool like the one in the link below if I find one that is hard to budge..

Just don't drop the new O2 sensor, keep the anti-seize on the threads, and you will be fine. I take it you are using new NTK/NGK sensors?

http://www.amazon.com/OTC-4673-6-Hea.../dp/B005LTJ01U

 

I did mine about 2 months ago. The hardest thing is getting the stupid cable tabs back in their holes. They come out easily. The sensors are easy to change ... like a spark plug. Get an O2 sensor socket. They are only a few bucks. I noodled around doing mine and it took me about 2 hours to do both, but I was in no hurry. Use anti seize in the threads if they don't have any.

 

Good point. Sometimes I use automotive store zip ties to secure O2 cables if the new cable tabs don't work out..

 

My 2 upstream O2 sensors didn't loosen easily. I sprayed them with PB blaster for days and used the O2 sensor socket with an impact wrench then a breaker bar but it wouldn't budge. Finally after getting the MAX fully warmed up the heated O2 sensors came off the y-pipe. If you have to use this method then wear gloves and sweaters to protect your skin from the hot exhaust pipes.

 

Thanks for the advice yes a have two different type of o2 sockets.anti seize will be used.
Whats the best place to get NTK/NGK sensors.

 

I go to a site like SparkPlugs.com or the NGK site to get the part numbers. Once I have the part numbers then I search out the best deal. I've bought sensors from internet Nissan stores like courtesynissan.com, then parts sellers like rockauto.com and advanceauto.com (with an internet coupon code), sparkplugs.com and from an eBay seller with a good rating. It is usually the seller with the best deal and availability at the time I need replace it. If you can wait a week for delivery then you can usually find the best deal online.

 

so the ones before the cat is upstream left and upstream right.

 

Yes, upstream is before the cat. My 2 upstream sensors had the same part number and were identical in cable length.

 

Post #5 is right. Run your car for a couple of minutes and get the exhaust pipe warm but not hot. I had no trouble getting mine out and they were the original sensors. I guess it depends how much abuse the pipe has had as to how hard they are to remove. Let us all know how the job went when you're done.