So I have this persistent P0141 code. Changed the sensor once, used NGK. Connections all look clean. Since it's post-cat (B1S2, NY XJ) really didn't get extraordinarily excited about a permanent fix.

Have needed to add a little antifreeze periodically for as long as I can remember (we're talking years). No visible evidence of external leak, does seem to blow off more condensation through the exhaust than one would expect during cold morning start-up.

Oil and anti-freeze clean. Runs smooth.

So my question is:

Of those people who pulled off 0331 heads, how many have seen cracks that, when you come down to it, are really benign?

IOWs, is every little mole mean you're going to get metastatic brain cancer?

 

Could be the head gasket letting coolant into the combustion chambers, and is getting burned off. Check the plugs and see if any look clean. Give it a compression test to see if anything pops up. Is the P0141 still happening? Check the fuse in the PDC.

 

No, now I have a P0157 instead! Well, never changed the other sensors before, so I ordered an NGK 23099. Waste of money doing post-cats, but I'm going to redo the front springs and isolators so I'll be under there anyway.

Plugs were normal fried when I did them last year, fuse looked good, switched the relays just for laughs (ruling out intermittent bad contact).

 

I reset the MIL and it's still out x2 starts but I guess that isn't going to last:

I'll see what happens after I slam in the '99.

 

Ooops! Forgot B1S2:

 

But B1S2 shouldn't be flat like that. That one's only ~a year old, but perhaps it has gone bad already (this is the one that was throwing 0141 codes).

Specifically, an underlying post-cat problem? Maybe there'll be something visible when I pull them out.

I thought people here were recommending NGK, that was the Gospel. Or is that NTK? Is there really a difference?

https://www.ngkntk.co.jp/english/corporate/brand/

That image of the 4 sensors mounted in the CA cat is everywhere, and there are the NTK part numbers. But now I see a couple threads where only Mopar is guaranteed to work.

https://www.cherokeeforum.com/f2/dow...-sensor-97928/

Anybody have some science for this?

 

Another pesky P0141 problem:

https://www.cherokeeforum.com/f2/98-...-fixed-155000/

I wish people would post follow-ups when they fix their issues.

I'm assuming they eventually fix their issues.

A lot of people post "Well, unless you change all of the sensors at the same time the planet will stop spinning!"

Is this true?

I mean, volts is volts, why should this make a difference?

 

Nice day in New England so changed out B2S2. B1S2 is still being contrary and I had a Pending P0141. Because it's dampened and not dead still theorizing that it's covered with some sort of biofilm. Or maybe it's just plain bad. I'll think I'll just change it out. $44.42 on Amazon...

 

Well, now I have a P0432. Certainly makes the question of "Why should you change all 4 sensors at once?" pop-up again. IMO I don't think using OEM makes a difference or not, perhaps it's you only need 4 of the same manufacturer. And NTKs should be good anyway. Waveforms look the same so maybe it was just a blip but kinda doubt it. Although it's a NY XJ I'm not in NY so I could use the Walker 52304 . Got emissions coming up in August so the tape approach will only go so far.

But this makes my original question resurface - do 0331s foul cats (and O2 sensors) more rapidly than "good" heads?

My antifreeze leak is literally infinitesimal and hasn't changed in years and years.

Course 19 years is a long time for anything and maybe it's just the cat's time.

The only thing that bothers me is that my NTK 23110 lasted only 14 months, and it's not "dead" it's "flat".

I need to read up on "pinning heads". Not going to let the terrorists win!

 

For starters I just realized you are in CT. Where? So am I.
So you had the O2 heater code. And it was not the fuse? What O2 sensors did you replace?
I ask because in my '00 I had a O2 heater code when I first bought the Jeep 6 years ago. Turned out to be just a fuse. It was a kind of running not really driveable project. Nothing crazy.
Anyway after I got everything straightened out and punched the Jeep through emmissions I took care of the other issues. After all that I decided to do whatever I could to improve gas mileage.
Basically 4 hole injectors and 4 new O2 sensors. Right after the Jeep threw a P0432. My thinking is that my old O2 sensors were lazy. I am guessing that they were original and had about 150K on them.
So lazy but not enough to know to throw the cat code. But when I put in new ones they were working properly and did.
Just a guess on my part.
And yes with a CA Emissions vehicle not registered in CA or NY you can use the Walker 52304.
Check down pipe. You might have to buy that which is 53440. I needed a new muffler and tailpipe at the time anyway.
So I just said screw it and bought everything new. I even bought the hardware from my local Jeep dealership for where the cat goes to the exhaust manifold.
But that is probably not necessary. I just wanted to have it incase.

 

I'm out Danbury way!

Fuses and relays were good when I checked a while ago. Can't hurt to look again but I'm O2 sensor code free right now.

Put in a B1S2 that a year later is wonking out. Sometimes it's 1.0V, other times it's like above at 0.4V. Got a new one coming. Just replaced B2S2, so yeah I think it's sending more volts back now.

Might just give in and pull the head too while I'm at it.

 

Only about 12 exits east from you on 84. Watertown near Waterbury.

 

Great!

Mayhaps I shall swing by and borrow a cup of 0331!

 

Still getting cat codes. I reset it, and it returns after a while (do not know what "a while" really is as I don't put a lot of miles or trips on it). Anyway, went down for emissions testing. Reset the MIL and figured let's see what happens down there. Passed testing. Turns out CT doesn't do "emissions testing" per se, they do OBD testing (I didn't read the old reports, they just would say "passed" and I would say "see you in a couple of years"). Darn, I wanted to know what the cat(s) is/are really doing before I changed the pre-cat sensors.

It would seem that a 2000 XJ ECU doesn't keep a very long history of codes ("Hey, you just cleared these cat codes an hour ago?") or Emission Testing doesn't look for it.

Guess I don't have to worry about increasing ZDDP and coating the cats anymore...