[ziggieice]

Some back story, I have a 2004 non supercharged 2-wheel drive xterra w 159k miles. A few months ago I was getting some really bad mpg and my SES came on, I got it scanned and my engine bay 02 sensors were tripped as well as the ones near the catalytic converter and a fuel level sensor that comes and goes?:

p0132 Air fuel ratio sensor 1 circuit high voltage
p0152 Air fuel ratio sensor 1 (Bank2) circuit high voltage
p0138 heated oxygen sensor 2 circuit high voltage
p0462 fuel level sensor circuit low input

The recommended part was engine wiring harness?
Well I did the trick where you would clean the ground strap washer and bolt for the engine bay's 02 sensors I had to actually relocate one of them as well as change the nut and washer because the original location was so badly rusted.
now I cant clear my codes as I dont have a scanner only a autozone readout but My SES turned off on it's own after about 200 miles of me doing that and has stayed off for about 160 miles after that but came back on and now I have p0430 catalyst system efficiency below threshold (bank 2) this is the only code with the previous still in memory
I assume that my 02 sensors are actually bad and the grounding wasn't an issue and me running lean for so long and putting up with the terrible gas mileage caused my cat to die OR I really did need to clear the codes so that my car can readjust itself to quit running lean. Is it true that the fuel level sensor can trip the cat's code, are there any work arounds? I will continue to do more research on this but I'm weary on buying a new cat. ANY incite is really appreciated!

 

[ziggieice]

The search continues

I still have no idea what to do whether I need a new wiring harness or new o2 sensors, I have 2 new sensors and my mechanic will install them soon. Fuse 14 is ok also, all fuses are ok in fact.
I still have symptoms of bad o2 sensors though like the rough idle and terrible gas mileage but the on;y code is for the the cat.

 

[GrnXnham]

I had similar codes on a few months back. I have an 02 with 197K

First I replaced the O2 sensors and that didn't fix it. Then I replaced the wiring harness. Problem fixed.

 

[ziggieice]

Jeez, I was afraid of this, did you happen to find where the fault was with your old wiring harness? Could you tell me how much you paid and where you got your new one?

 

[GrnXnham]

The place where the wiring harness connects to the engine corrodes over time. The mechanic got a new one and cleaned up the connection point for a better connection. Can't remember what I paid and I don't remember the breakdown because I had other work at the same time. Besides, in a different market, there are different prices.

You might be able to find the connection point yourself and try just cleaning the corrosion off. Maybe you can fix this yourself for free.

 

[ziggieice]

The place where the wiring harness connects to the engine corrodes over time. The mechanic got a new one and cleaned up the connection point for a better connection. Can't remember what I paid and I don't remember the breakdown because I had other work at the same time. Besides, in a different market, there are different prices.

You might be able to find the connection point yourself and try just cleaning the corrosion off. Maybe you can fix this yourself for free.

Well the wiring harness connects to the engine in a lot of different places, I assume I need to follow the leads for the 02 sensors?

 

[ziggieice]

I still need to find where exactly I need to look to see if there is corrosion before I drop money on a wiring harness, does anybody know where GrnXnham is talking about?

 

[ziggieice]

Still looking for answers, anybody?

 

[beef tits]

Any sign of exhaust leakage on the manifolds?

 

[ziggieice]

No, none

 

[beef tits]

I'd suggest investing in an OBD-2 scanner. You don't need a fancy one, a $26 no-frills device works fine.

https://www.amazon.com/Diagnostic-S...730&sr=8-2-spons&keywords=obd-2+scanner&psc=1

Scan, clear and see what happens. I get random codes here and there that I clear and never see again.

I'd suspect bad cats before bad O2 sensors, it's pretty rare that O2 sensors actually fail. I also drive a 2000 which is probably a lot more likely to have the cats go bad.

 

[ziggieice]

I said in a previous thread that first my sensor 1 bank 1 (i believe) 02 sensor went bad, then shortly after all my 02 sensors went, THEN my SES light turned off on it's own and stayed off for 200 miles then came back on with only a new code, p0430 catalyst system efficiency below threshold, and recently my SES turned off on its own again but came back on withing 20 miles, Do you not suspect this is the work of a faulty engine wiring harness? I wish someone would tell me which of the many points I need to get the corrosion off. How can I test visually for a bad cat?

 

[beef tits]

You also said you didn't have a scanner. I highly recommend you drop $20 and get one. It's a critical tool to have if you are going to drive shitty old trucks like ours.

I've never heard of or experienced a bad wiring harness on mine so I can't help you there other than suggest that you might have more than one problem. Or maybe you don't and you need to clean more grounds. Either way it will be a hell of a lot easier to diagnose if you have a scanner. Unless you like going to Vato Zone every other day.

Also, dirty grounds do not equate to a bad harness. Wiring harnesses don't just go bad unless they've been hacked into or modified or damaged in some way. Unless your car was in a wreck, owned by a moron, or has severe corrosion issues I would rule out a bad harness.


Regarding cats;

The best way to check your cats is to take an IR temperature scanner and see what the temp rise is across the cat after it's been running a while. Consult Google for more details but temp should be hotter on the outlet, I believe.

Since you balked at buying a $20 scanner, I am guessing you don't want a $500 IR. Your other option is to remove and inspect them. If they are bad you'll see obvious melting or the core will be loose, or turning to dust or rattling around. If it still looks like a new cat inside, chances are it's not bad.

The cracks in my manifold were so small I could barely see them at first, and the sound wasn't that loud. However, leaking manifolds will lead to your cats going bad and O2 sensor CEL lights. This is a very common problem on the earlier models.

 

[ziggieice]

In my research it seems first gen xterras have a "Technical Service bulletin" about the wiring harness going bad. I guess I could buy a scanner, those also clear codes? what other grounds do I need to look at? Would you know anything about what GrnXnham said, So far he is the most relatable but has gone quiet. I appreciate you getting back with me

 

[beef tits]

Yes, the scanner will clear as well as identify codes. It's the best $20 I ever spent.

I would look for that specific TSB and see what they say. Again, I have not had this problem so I don't know specific grounds to check. Then again, they are pretty easy to find and you could probably just clean them all pretty fast. Any wire (typically black) that is bolted directly to the frame, trans or the engine is probably a ground.

 

[ziggieice]

I actually dont know where to find that, Ive only seen it mentioned in a few threads with problems similar to mine, I actually cant find a thread here that states it but I found the other one I saw her in post #7 http://x.nissanhelp.com/forums/xterra/8233-all-four-o2-sensors-read-bad.html

 

[JLBinHSV]

Have you replaced the cracked manifold(s)? If so, was doing so worth the effort?

 

[ziggieice]

Have you replaced the cracked manifold(s)? If so, was doing so worth the effort?

I dont have cracked manifolds

Here is the other thread that mentions the 2004 service bulletin http://www.clubxterra.org/forums/showthread.php?t=20845

 

[JLBinHSV]

My question was aimed at beeftits. Sorry for the confusion.

 

[beef tits]

My question was aimed at beeftits. Sorry for the confusion.

I replaced them with headers, CEL eliminators and added secondary cats as the headers eliminated the primary cats.

Runs great now. Not a huge power increase but the headers were only a little more than the 02-04 style manifolds which are the only other good option for replacement IMO.

Replacing the 00-01 manifold with another 00-01 manifold is just asking to have to do it all over again.