You're not including a lot of info here. What year is the car? Have you tried clearing the faults and seeing if they come back? Does the car run any differently? In my experience it is a good rule of thumb to use OEM parts when it comes to emissions parts like MAF's and O2 sensors. They're finicky parts and I've never had good luck with aftermarket myself. A 2 second google search returned a whole bunch of O2 sensor videos and other info for the G35. Did you even search? I don't mean to be that guy but you have to take some initiative here besides making a forum post and expecting to get all the answers handed to you bro.

 

The OEM ones are Delphi, you can buy all 4 sensors right now for about $350 on rockauto.com and if they're really corroded it could take up to 30 minutes per sensor to change out = 2 hours of labor. I have no idea why he's trying to charge you 8-9 hours of labor so I would definitely find a different mechanic.

Did you get an itemized billing estimate? What on earth is he charging so much for? Even buying them from Infiniti the parts only come to $700 so he wants to charge you 4 hours of labor for what would be a 2 hours job in the WORST conditions? I honest to god bet you could actually get that done cheaper by having Infiniti do the work lol.

 

 

 

 

Check the part numbers. If it fit both side it wouldn't have different part numbers

 

iirc the upstream O2 sensors have a black harness and are interchangeable, the downstream ones are side-specific and I think the green harness one is left side and the blue harness one is the right side. Probably need to double check that though I might have the left/right backwards.

 

I changed one of the upstream sensors on my 04' a coupe months ago. I ended up cutting the wires off and using a 1/2" drive impact socket to get it out. Any other way would have rounded it off. If that happens the whole exhaust manifold has to come off.

 

Not necessarily, my GF has a 97 Nissan truck with 225K miles. One of her rear O2 sensors was corroded so badly the sensor wasn't coming off no matter what we tried so I took it to a local muffler shop. The charged me $25 to cut a new hole in the pipe and weld a new bung in about 2 inches in front of the old sensor. They used a plasma cutter to make the hole which was cool to watch. Sensor screwed right in, hooked it up and it's been working fine for 2 years. Took them less than 15 minutes to do the work.

 

Good luck doing that on a front sensor. You can barely get tools in there to change it yet a plasma cutter and tap. The rear sensors are simple if they give you a hard time since the cats simply unbolt and break away. If you don't play around and use a good 1/2" impact first it almost always comes out. (Think I've only had a couple not come out in over 10 years)... It may take all the threads with it if the sensor threads are fused to the bung but it will come out

On the O2 sensors. The "Upstream" O2 sensors left and right are the same. For 2004 models RWD use narrowband upstream sensors and the AWD cars use wideband upstream sensors. The Downstream sensors are different length so they are different part numbers for left and right. RWD and AWD downstreams are the same part #'s and are narrowband only.

 

Blue Dream thank you for confirming it won't throw codes if there's a slight position change on the sensor. If my cats ever go I'm going to make my own custom catted ART-style pipes using cheap universal cats (with comparable flow ratings to OTS G35 HFCs) and custom length J pipes, and that was the last thing I needed to know.