I have a 2001 Cherokee sport with the original manifold cats and exhaust. After having a shop clean the throttlebody with seafoam, I'm now getting the P0432 code. So, step one after finding no exhaust leaks, I'm going to replace all four O2 sensors. Following CCKen's advice I've ordered the NTK Brand and parts that he specified in a different thread. My question for those of you who've done this before is only this: Is there anything special I should know or consider before replacing these sensors myself when they arrive? Any tricks or pitfalls of this particular repair? It would seem pretty straightforward, right?

 

I would recommend an O2 sensor socket/wrench/tool etc. Crowfoot at least.

 

Only tricky part can be getting the old O2 sensors out. I have an O2 sensor socket but usually end up resorting to a regular wrench with big pipe helper. If you can get a regular wrench on them, a few whacks with a hammer usually break them loose and then you are good to go.
Hopefully it's not the actual cat. If it is, I have had good luck with the eastern catalytic converter brand from amazon. If you have to replace the cat, it's most likely easier to replace the whole system since everything gets fused together after 16 years. I just had to replace the original cat on a 98 Cherokee. The inner honeycomb part had broken loose ans was rattling around pretty badly.

 

Had the P0432 code with my CA Emissions '00. Research says it could be a variety of things. Exhaust leaks, vacuum leaks, O2 sensors, and fuel trims if not the cat. Thing is 90% of the time it is the cat. Well after checking everything as best I could replaced the cat. Been fine ever since. If I were you I would only replace downstream rear for the time being. If it is an O2 sensor and not the cat I think that is the one that would be causing the problem. Nothing wrong with swapping them all out. People say about 100K and they should be changed but I would see what happens with just the one. I went Walker with the cat, front and rear, and did my whole exhaust. Just so happened that I needed a new muffler and tailpipe anyway.

 

Last time I replaced the O2 sensors, I used a combination of wrenches to loosen the sensors. I have a 7/8 inch wrench and I "rented" the O2 wrench set from Autozone. Where I didn't have the room to maneuver the 7/8ths, the crowfoot socket worked better than the straight socket. I warmed up the engine before attempting to loosen the sensors.
Good luck!

 

warming it up first might be a good idea!
I assumed it was just a regular socket, i didnt realize there was a 'special' 02 sensor socket.
i'll be getting my upstream sensor in the next few days for my '98.

 

Warm up x2 also pigtail can be cut off and box end wrench makes easy work in tight space. Then use open end wrench to tighten down.

 

I've only ever used a 7/8 wrench (on any vehicle I've ever had). With that said, I only have 2 sensors on my 97 that are easily accessible... not sure where the sensors are on the 4 sensor setup, CA emissions in guessing?

 

Heat is your friend. There is no need for a cheater bar if you heat it up first. Either run it long enough to get the exhaust system up to temperature, or use a torch on the bung fitting around the sensor, not on the sensor.

The torch approach gives you fewer opportunities to burn yourself on a hot exhaust system.

If you don't use an O2 sensor socket, at least use a 6 point socket, NOT a 12 point. If you round that sucker off you will be cursing yourself.

 

Soak it with pb blaster before you take it on the highway and let it get nice and hot. Put either your wrench or socket on it and give it a go, once you get it off make sure you put anti sieze on it and plug it back in. Also, make sure you zip tie the wire so it does not rub on the drive shaft, learned that the hard way