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Discussion Starter · #1 ·
Hey all, first time posting, hopefully doing this right. So I have a new to me 2005 tj unlimited with 178k on the ticker. Just replaced all 4 o2 sensors with ntk's and did the tsb yesterday. Driven it bout 40 miles, cel came back on with p0153. What gives?
 

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I assume there is some damage to the wires.

The O2 wires are low hanging fruit. Every time I pull a code for an O2 sensor I check the wires and connections. I refuse to blame the actual sensor because I have seen them last well over 200k mi. I actually just had this code on my LJ and it was a small hole in both the loom and wire. I just put some electrical tape on the wire and replaced the loom with a more rugged heat resistant split loom.

The wires run through a protective loom that can easily be damaged by debris or rubbing on the exhaust mid pipe.

I would pull the loom up as far as you can to inspect the wires.
 

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Hey all, first time posting, hopefully doing this right. So I have a new to me 2005 tj unlimited with 178k on the ticker. Just replaced all 4 o2 sensors with ntk's and did the tsb yesterday. Driven it bout 40 miles, cel came back on with p0153. What gives?
Very likely one or both of the two small pre-cats are bad. Mine did the same thing, new O2 sensors didn't help mine either.

Then one of the two pre-cats puked its guts out and clogged the main cat so thoroughly the TJ's top speed on the highway suddenly dropped to 5 mph. Replacing all of the cats cured everything. No more CELs, still using the same O2 sensors.
 

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Discussion Starter · #4 ·
Ok, I'll definitely check the wires in the loom. Noticed some of the loom was disinterested in the engine compartment so I'll check there first. Before the ntk o2's, I got p0133 and 0153. Replaced with Bosch o2's and the light went out. Came back on, just p0153, replaced o2's with ntk. A day later the light came off after performing the tab, then 40 miles later came back on.
I think 0153 is before the cat so I may be wrong, but wouldn't the code read the downflow cat if the mini cats were bad?
 

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Ok, I'll definitely check the wires in the loom. Noticed some of the loom was disinterested in the engine compartment so I'll check there first. Before the ntk o2's, I got p0133 and 0153. Replaced with Bosch o2's and the light went out. Came back on, just p0153, replaced o2's with ntk. A day later the light came off after performing the tab, then 40 miles later came back on.
I think 0153 is before the cat so I may be wrong, but wouldn't the code read the downflow cat if the mini cats were bad?
You replaced the O2 sensors with Bosch O2 sensors (which have a bad reputation in Jeeps), that didn't help. Then the Bosch O2 sensors were replaced with the correct NTK sensors and that didn't help either. So your issue of CELs are not likely caused by a bad O2 sensor.

The diagnostic system is not perfect, it can't always pinpoint problems because many conditions can be the result of combinations of other issues. I used to be a systems engineer for large scale computers... mainframes and supercomputers. We had diagnostic routines we would run to help isolate problems. Very often the diagnostics did nothing but throw curves and mislead on the true problem. In other words, diagnostic routines... sometimes even very sophisticated diagnostics... won't always point to the true problem.

I did explain I had the exact same symptoms/CELs as you and, like you, replacing the O2 sensors didn't help. The problem and the fix turned out to be the catalytic converters. That's all I can offer.
 

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Discussion Starter · #6 ·
Cool. Thanks for the info. I didn't mean to step on toes, I'm used to working on carbureted vehicles, Diesel engines, and the older 4.0 engines with plugs and wires. im getting a bit frustrated with this thing as every other day I'm ordering parts for it. Today just saw in the work parking lot I'm dripping coolant from the water pump. And it's still running rough at an idle. Oh well. That's the way it goes sometimes.
Gonna take off the cats and check them out this weekend. Along with wiring. And a water pump.
 

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Discussion Starter · #7 ·
Figured this out and was a dumb mistake on my part. All three cats are in excellent shape, even after not taking them off, but I DID look at the solder I used on the wires and totally used plumbing solder. Big no no on electrical. After cutting out the plumbing solder, I used electrical solder and shrink wrap to make the wires on the tsb I had performed look nice. 3 days, no CEL!!! Don't use plumbing solder for wires!!
 

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Figured this out and was a dumb mistake on my part. All three cats are in excellent shape, even after not taking them off, but I DID look at the solder I used on the wires and totally used plumbing solder. Big no no on electrical. After cutting out the plumbing solder, I used electrical solder and shrink wrap to make the wires on the tsb I had performed look nice. 3 days, no CEL!!! Don't use plumbing solder for wires!!
Yep using plumbing solder was a big no-no. Plumbing solder is acid-core which is obviously not good for wiring. Electrical solder has a rosin core.
 

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Catalytic Converter Replacement

Very likely one or both of the two small pre-cats are bad. Mine did the same thing, new O2 sensors didn't help mine either.

Then one of the two pre-cats puked its guts out and clogged the main cat so thoroughly the TJ's top speed on the highway suddenly dropped to 5 mph. Replacing all of the cats cured everything. No more CELs, still using the same O2 sensors.
Hey Jerry, where did you find your catalytic converter with the 2 pre-cats, when you did your repair. I can't seem to find a replacement with 4 o2 sensors ports. Everything I find only has 2 ports post cats. Thanks
 

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Hey Jerry, where did you find your catalytic converter with the 2 pre-cats, when you did your repair.
I got lucky, the Earth, stars, and Mars must have been in alignment when it happened to me. I barely made it to a friend's house on the way home who happens to be a Jeep builder. And for the first time ever, according to him, he just happened to have a near-new take-off assembly that had all three cats from an engine conversion ready to be bolted in. He installed them for me, we even reused my existing O2 sensors. It all worked perfectly, it's still running great 6-7 years later.

Try the Magnaflow website at Magnaflow Home. They have pretty much all the various catalytic converter assemblies our TJs use.
 
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