It's my turn to ask for help!

badlieutenant

badlieutenant

TJ Addict
Joined
Nov 7, 2015
Messages
1,267
Location
News Braunsfels, Texas
So I've got a couple CEL's and I've had them since I've owned the Jeep. I haven't experienced any performance degradation or anything of the sort. I actually disassembled the instrument cluster (gosh, like 50 tiny screws) and put some black electrical tape over the CEL LED and Airbag LED (I pulled the fuses to the airbags so my kids can ride in the front).

I'm getting P0421 and P0152. The previous owner said his mechanic thought it was bad O2 sensors so he replaced them with some shit brand, not NGK/NTK! Basically, if it is the O2 sensors, replacing them with whatever crap brand he used might have very well not fixed the problem. My mechanic, who is a very good man and 100% honest (he is a Freemason and really is a pillar in the community) is by no means a Jeep expert... I'd trust him to rebuild the motor and fix most issues but I trust our local wranglerTJforum experts to point me (and my mechanic) in the right direction. He said he tested the O2 sensors and stated that they're "cycling" correctly and believes it to be an issue related to my catalytic converters.

He referred me to a muffler shop that does the work for him but if I'm going to need to replace the cats, I'd much rather get a nice new full aftermarket exhaust system (as long as it doesn't throw codes or have the potential to create emissions issues when my nice conservative town folds to the liberal aggression out of Austin). He said the muffler shop would simply cut and then weld on new cats... I'm not a fan at all of cutting up my pipes and welding on new cats.


"Problem" #2 isn't exactly a problem but I do need some help. A friend gave me this:

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It's a hitch that came off of his earlier year model TJ... I believe it's a 2000 or 2001. I can't figure out how to install the damn thing. It seems to have all the hardware and he said it will also use my existing bolts and that it should just "bolt right up". I consider myself pretty damn mechanically inclined and am embarrassed to say I can't figure it out.

Thanks in advance guys.
 
Found this on another forum hope it helps

P0421 OBD-II Trouble Code
Technical DescriptionWarm Up Catalyst Efficiency Below Threshold (Bank 1)

What does that mean?Basically this means that the oxygen sensor downstream of the catalytic converter on bank 1 is detecting that the converter is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.


SymptomsYou will likely not notice any drivability problems, although there may be symptoms. The code may be more likely to occur after the engine has had numerous cold starts in the past 1-2 days.

CausesA code P0421 may mean that one or more of the following has happened:

*The catalytic converter is no longer functioning properly
*An oxygen sensor is not reading (functioning) properly
*A sparkplug is fouled up




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Start with spark plugs (unless you changed them recently), if that isn't it, it's either the O2 sensor or your cats. It stands to reason that both of them need to be replaced, especially if they're the original ones still on the vehicle (being a 10+ year old vehicle and all).
 
I typically pull the entire exhaust when cutting/welding pipes. It allows the person welding to lay a good bead all the way around the pipe.

I have always understood that touching the ends of the O2 sensors can be bad for them. So I always am carful with them.

If it were me, get a high flow cat(s) and run them with an aftermarket muffler (purley for sound).
 
Chris said:
Start with spark plugs (unless you changed them recently), if that isn't it, it's either the O2 sensor or your cats. It stands to reason that both of them need to be replaced, especially if they're the original ones still on the vehicle (being a 10+ year old vehicle and all).
Click to expand...

So much $$$. :-(

I'd love a full exhaust system replacement with a nice growl that's compatible with our 06's and their four O2 sensors.

Know of any direct bolt-on replacements?
 
badlieutenant said:
So much $$$. :-(

I'd love a full exhaust system replacement with a nice growl that's compatible with our 06's and their four O2 sensors.

Know of any direct bolt-on replacements?
Click to expand...

I don't know any full direct replacements.

When I mention that I pull the entire exhaust, I also do my welding and then put it back in.

I believe the banks muffler or the magnaflow race mufflers are ,those are my favorites behind the 4.0's.

Any of the smaller high flow cats work. Just match the pipe diameter for the 4.0.
 
@Chris I need to double check but I'm pretty sure the plugs were replaced at 60k miles.. I've got almost 90k now.

I really wish there was a better way to diagnose the issue. The PO sold it to me with under 80k; if he had only taken it to the dealership... it'd probably have been covered under the emissions warranty. I have a feeling it's either the cats (most likely) or the O2 (second guess).

Thing is, this isn't something that must be fixed... I'm not having any performance issues and the CEL has basically been disabled so the light won't bother me.
 
My money is on the cats or the O2 sensor as well. Those things should be replaced anyways as preventative maintenance, so I would replace them all at once, when the funds permit.
 
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