I have an 04 Rubicon w/ 183k miles and I’ve been receiving this code P0423 code after short idle periods. Assume it’s either a cat and/or a sensor in bank two. Any suggestions? Should I go ahead and change out the entire cat system (all 3) or just change out the four sensors? No performance issues or any exhaust leaks that I can tell. Also, how difficult is the entire cat system to change? On a scale of 1-5 on technical abilities, I’m probably a three. No welding though. Thank you!
Code P0423
- Thread starter C311bailey
- Start date
With 183k miles you are at the end of the life cycles of the 02 sensors and the precats, assuming they were replaced at proper intervals.
I would replace all four 02 sensors with NTK sensors.
If 02 codes re appear, you'll then need new precats.
I would replace all four 02 sensors with NTK sensors.
If 02 codes re appear, you'll then need new precats.
Anyone have a suggestion on if this is a weekend project to replace the cats or if I should take it to a shop? Again, I’m about a 3/5 on the tech skills level. Just don’t want to get in over my head.
When my 02 sensors and cats went out I purchased an Evan Fisher cat replacement, roughly $265. It was literally a bolt on project, took me half a day.
These dad gum upstream 02 sensors on our TJs are so critical to engine performance and gas mileage, I keep a spare, new NTK 02 sensor in my special, secret "TJ PARTS BOX" for both my 97 and 05 Tjs. 
I know @Chris had posted a list of o2 sensors for each year and engine and he referenced NGK. @Jerry Bransford said they were NTK in another post. I was just wondering. Luckily mine are still ok.
Yes, NGK / NTK is the brand you want to use.
This is the post you're referring to: The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread