Failed Smog Code 172

[SHOMac23]

Hi I'm brand new to the forum. I have a 95 SHO, 3.2 Liter, 113,000 miles. Recently replaced water pump, alternator, valve gaskets (oil in them), and battery to name a few things. I just failed smog in california. I pulled the 111 and 172 codes today. My next step is to replace the front two O2 sensors. I am hoping I do not need to replace the rear, or the cat. Hopefully this will help with my high CO2 readings. Any advice or help would be greatly appreciated, and again, thanks for helping a new guy out.

Thanks

 

[jmpSHO]

172 is lean on right bank I would just replace that sensor.

 

[SHOMac23]

I've read that this is a fairly easy replacement, anyone have any tips or pointers. I really hope this will let me pass Smog.

 

[jmpSHO]

It's the rear sensor and yes it is very simple. Auto parts stores sell a tool made to remove the sensor but I have used a moveable wrench at times but I think having the correct tool makes it easier. It can be removed from either the top or the bottom I only tried it from the top once when I was having trouble removing it, I think it was cross threaded. Anyways I would do it from the bottom you just have to reach up without really seeing and disconnect the sensor and then remove it from the y pipe.

 

[SHOMac23]

Thanks for your help, and one last thing by the rear sensor you mean under the hood not the rear sensor after the cat correct?

 

[SHOtime2511]

there are no sensors after the cat.only SHOs 96 and newer come with them.
the night before you change the sensor spray some PB blaster around it. a large crows foot wrench will make quick work of it.
another thing you can do is pull the spout connector to pass testing.

search "spout" for more information.