P0174 and P0175 codes after replacing the catalytic convertors

Camdenst

TJ Enthusiast
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Good morning guys,

Anyone have any idea why I would throw a p0174 and a p0175 after replacing the cats on a 2005 ljr.

Backstory: I had a p0421 prior to the install and went as far as replacing the sensor with the recommended ngk last summer without resolve. I was beginning to hear the exhaust leak as well, which made me really think cats.

This weekend I replaced the cats and disconnected the batter and was good, no check engine light. Then, after about 20 mintes the 0174/0175 popped on.

Thanks in advance.
 
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I'm guessing a new sensor would be a good start point. 174/175 are both 2/1 one being too rich the other too lean. That would be bank 2, up stream sensor ngk 23160?
 
My opinion is that replacing one sensor is a bad idea. The better idea is to replace ALL 4 sensors at once, unless the others are really new.

So I would do that, then clear the codes with an OBDII reader, then see what happens.
 
I believe I did the bank 2 downstream last summer. Its got 114k, I couldn't tell you if the sensors are original. Outside of unknown age of the sensor, why all four? Is it to just rule it out?

At the moment I don't have a obd port. I accidentally hit it and it exploded into a million pieces. I have looking for a wiring diagram and dreading/ waiting till emissions time when it has to be done.
 
That OBDII port might come in handy, LOL!

There's a good chance all you have to do is reset those codes and they might not come back. Remember... Ockham's Razor!
 
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That OBDII port might come in handy, LOL!

There's a good chance all you have to do is reset those codes and they might not come back. Remember... Ockham's Razor!

I will second this that’s the only way I was able to chase all my o2 issues down and fix them also agree with doing all 4 at once


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Love it, haven't heard that phrase in a long while. Any risk in just starting with the one and going from there?

It's almost always true. Like I said, see if you can clear those codes. You might be surprised :)

You can just start with one, but with as cheap as they are, I think it makes sense to do them all. They work together, so I'd probably at least replace the two upstreams together (or downstream).
 
I'm not sure I'm familiar with that one!

Thanks to @Jerry Bransford for this one.

The Peter principle is a concept in management developed by Laurence J. Peter, which observes that people in a hierarchy tend to rise to their "level of incompetence". In other words, an employee is promoted based on their success in previous jobs until they reach a level at which they are no longer competent, as skills in one job do not necessarily translate to another.