Code P1168 and P1286

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Code P1168 and P1286

Postby palmerwmd » Mon Jan 15, 2018 8:52 am

Came on after I used B12 Chemtooler on a hot day and ran it hard-ish (to clean out gunk I surmised I had in the system since I been running only very short trips prior month with it)

At first i was confident code would go away on its own as harsher cleaner sometimes do this until the car relearns.. but it hasnt in 4 months and 1500 miles. (Except for 1 day but then it came back)
I did also have a P0430 at first but that did go away on its own..

Back then a tech I trust and who knows my truck told me over the phone (since i now live 2 hrs away): "this means your cats are running freer than stock no worry about blowback into engine. Codes not a big deal you can just keep running. I have a trick in the shop to make it go away permanently but since u live in a non emissions county dont worry about it".

Of course talking to the man over the phone is not the same as him actually going at it.
Truck runs strong, fuel economy normal.

What do the cognoscenti on here think?


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Postby smj999smj » Mon Jan 15, 2018 1:30 pm

I'm assuming your buddy is referring to the P0430 code when he mentions your catalytic converters are running freer than stock? The only way your converters would run "freer than stock" is if you were to gut the converters or replace them with converters with less substrate inside them...which still may not make them run "freer." That's nonsense! P0430 means that the ECM is detecting that the Bank 2 upstream converter (your driver side, front) is not breaking down emissions efficiently based on inputs from the air/fuel ratio sensor in front of it and the oxygen sensor behind it.
That code would made sense in relation to your other codes, P1286, which is a heater malfunction code in the Bank 2 upstream air/fuel ratio sensor and P1168, which is an electrical circuit malfunction of the Bank 2 upstream air/fuel ratio sensor. It's impossible to say for sure whether the sensor heater element was damaged by using the B12 Chemtool additive (Nissan doesn't recommend the use of any additional fuel additives and most name brand gas companies already have cleaning agents in their gasoline) or it's just coincidence. However, by the codes you have triggered and how long they've been on, I would say you need to replace the upstream air/fuel ratio sensor on the driver's side, aka Bank 2.
I would go for NTK # 25685 (which is the OE part) or Denso # 2349036.
Chances are your catalytic converter is fine and the efficiency code was a result of the issue with the air/fuel ratio sensor.

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Postby palmerwmd » Mon Jan 15, 2018 3:46 pm

Thank you Sir! :)

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Postby palmerwmd » Mon Jan 15, 2018 4:09 pm

PS; So if I replace that O2 sensor.. Will the heater code still come back? or are they on the same part assembly?

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Postby disallow » Mon Jan 15, 2018 5:48 pm

I believe so as the sensor is heated.

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Postby palmerwmd » Tue Jan 16, 2018 7:34 pm

Cleared the code 2 days ago.

Started/shut off the car about half a dozen times since then.
Hasnt come back one but my driving was mild and short distances.

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Postby smj999smj » Wed Jan 17, 2018 3:02 am

A heater element is built into the sensor. The quicker the sensor heats up, the quicker the ECM can go into closed loop, so that's why it's in there.

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Postby palmerwmd » Wed Jan 17, 2018 6:16 am

So it might be just the heater element that's causing both codes?

So this may mean if I war up the car gently then the O2 sensor will be at efficiency and I dont have to worry about bad AF ratios in my engine?

:)

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Postby smj999smj » Wed Jan 17, 2018 10:56 pm

It means if the sensor heater is bad, stop screwing around and replace the air/fuel sensor! :wink:

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Postby palmerwmd » Sat Jan 20, 2018 7:03 pm

So after I cleared it last and i thought I might be in the clear it didnt come on for 6 days.

Most of my driving was milder though.
Today I drove some more again and a bit faster (touched on 80 mph for abit)..


After I shut it off to get gas a minute after I started driving it poppwed acode again..
This time just one and its different! :oops:

P0174..

I look it up has multiple causes listed.
Intake air leaks
Faulty front heated oxygen sensor
Ignition misfiring
Faulty fuel injectors
Exhaust gas leaks
Incorrect fuel pressure
Lack of fuel
Faulty Mass Air Flow (MAF) sensor
Incorrect Positive Crankcase Ventilation
(PCV) hose connection


But no2 is same as the other codes isnt it?

I just had a big expense hence my delaying :)

---Would u still say faulty front Ox sensor?

---Also at this point we are pretty sure its not the cats, right?
Because I have a chance to pick up some working OEMs for a good price..

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Postby smj999smj » Mon Jan 22, 2018 2:54 pm

You can't really condemn the converter(s) when you've had issues with the heated oxygen sensor. Anything that can cause the engine to not run efficiently has also the potential to trigger catalyst efficiency codes (and possibly damage the converters, as well).
P0174 is a system lean code for Bank 2. Again, we are dealing with the driver's side engine bank. Since this code is a new code, I can't say that we are dealing with the same issue. It wouldn't hurt to confirm proper fuel pressure and check for any sources for unmetered air leaks, such as splits in the intake ducts, split or disconnected vacuum hoses, etc. As you already pointed out, a faulty upstream air/fuel ratio sensor (or oxygen sensor, if you prefer) can cause this code to trigger.
I can't tell you what to do. The right answer would be to get an expensive scan tool and factory service manual and perform the diagnostic steps for the given code until you isolate the exact cause of the problem. As far what I would do if it were my own vehicle and based on my former experience as a Nissan tech, I would start by confirming there are no intake or vacuum leaks and, if none found, I would proceed with replacing the driver's side air/fuel ratio sensor, erase the trouble codes and see how it goes from there. Hopefully, that will be the fix for all of the issues.

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Postby palmerwmd » Mon Jan 22, 2018 5:14 pm

Thank you for your patient and complete replies.
I know a shop I trust for performance and price but its 2 hrs away in Alexandria..

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Postby palmerwmd » Tue Jan 23, 2018 4:59 pm

Ouch!.. I priced the part the cheaper of the two was $317 at my local shop installed add an hour labor so over $400 plus tax..

I may have to sell one of my revolvers... :oops:

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Postby smj999smj » Tue Jan 23, 2018 6:37 pm

Get the part from Rockauto.com; it'll be a lot cheaper. They have both NTK and Denso brand.

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Postby palmerwmd » Tue Jan 23, 2018 8:21 pm

Then I will look for a place which will install it for me :D


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