So my girlfriends Liberty is showing code P0420. Looking at the live data on my scan tool it looks like it could possibly be a lazy upstream o2 sensor. The voltage is changing rather slowly.

Has anyone replaced this o2 sensor?

After briefly looking at it, it seems to be in a really tight spot.

I am hoping for some luck and good info as to the best way in replacing it. I really dont want to have to drop the front drive shaft to remove and replace it. I don't have access to a lift at the moment and removing the drive shaft laying on the ground would be a pain.

This Liberty apparently has the old vertical style cats as well.

Any info would be appreciated!

Thanks

I have replaced all of them, but i did it the same time I changed a front pinion seal.....so.......yeah, that helped. Honestly, the other side upstream is the one that gave me more fits. The threads were stripped, had to drop whole exhaust on that side weld new bung on. That was fun...

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