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-   -   Engine Code P2A00 (https://x.nissanhelp.com/forums/sentra/18012-engine-code-p2a00.html)

DareDevil 03-22-2011 05:39 PM

Engine Code P2A00
 
I have a slightly modified 2006 SE-R Spec V with approximately 55,000 miles. I have been trying to figure out this code for over a year now.

There are no internal modifications to the engine, only a cold air intake, Megan racing header, and cat back exhaust.

Almost immediately after having my header installed, my SES light came on and I pulled the code P2A00. After an enormous amount of research, I learned more about the code, and replaced both O2 sensors. I also cleaned the MAF sensor with the appropriate cleaner. I reset the SES light, and it never fails to return after no more than 20 miles. I have theorized that perhaps I should move the primary A/F sensor from the bung in the upper portion of the header to the bung after the collector as the upper bung only reads cylinder 2.

I am certain there are no exhaust leaks as I have recently replaced the exhaust gasket with a multilayer OEM unit.

I read one post on this forum that said something I hadn't seen before after searching for a solid year on the internet. Is it necessary to use the Consult III and clear the "self learn" in "work support?"

If that's true, is there any other way to clear the "self learn?" Is this similar to performing an "idle air relearn?" I know how to do that using only the key, gas pedal, and SES light.

Thank you in advance for your help.

NissanTech 03-22-2011 07:31 PM

Quote:

If that's true, is there any other way to clear the "self learn?"
Yes it is.

Quote:

Is this similar to performing an "idle air relearn?"
Here are the instructions:

1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF.
3. Disconnect mass air flow sensor harness connector, and restart and run engine for at least 5 seconds at idle speed.
4. Stop engine and reconnect mass air flow sensor harness connector.
5. Make sure DTC P0102 is displayed.
6. Erase the DTC memory.
7. Make sure DTC P0000 is displayed.
8. Run engine for at least 10 minutes at idle speed.

DareDevil 03-24-2011 09:54 AM

Thank you NissanTech, you're awesome!

I had taken the car to the dealership last year and they were able to get the SES to stay off long enough for them to smog the car, but it came back within 100 miles of driving. I asked the service manager what they had done but he said he didn't know.

Do you think that even though I replaced both O2 sensors that the a/f sensor could have already failed?

Is there any benefit in moving the a/f sensor further downstream past the collector?

DareDevil 03-26-2011 07:36 PM

I just picked up a cheap code scanner to help me with this. I followed the instructions above and did indeed display code P0102. There was also a pending code of P0102, and also a pending code P0113. I read the definition and possible causes. Should I be concerned about this, and could it be contributing to that P2A00?

NissanTech 03-26-2011 08:43 PM

p0102 = Mass or Volume Air Flow Circuit Low Input

P0113 = Intake Air Temperature Sensor Circuit High

Both codes are for the Intake Air Temperature Sensor. The sensor is probably disconnected or damage, or the air filter is dirty.

The Intake Air Temperature Sensor is inside the air flow meter. I suggest checking the air filter and replace it if necessary. If the filter is OK, check for debris obstruction the air flow. If there are no debris try cleaning the air flow meter and clearing the code.

Quote:

Should I be concerned about this
Probably, if there is a code stored in the ECM, then something is not right.

Quote:

could it be contributing to that P2A00?
It is possible that is related to the P2A00 code.

DareDevil 03-26-2011 09:34 PM

It popped those codes after I followed tour instructions above to clear the computer self learn function. After starting the car with the MAF disconnected, both codes appeared. I have an AEM short ram intake installed, but cleaned the filter less than 5000 miles ago. In the past, I have cleaned the MAF with MAF cleaner spray. Is it possible I damaged it?

DareDevil 03-27-2011 09:20 AM

Ok so here's an update:

I've made it 16 miles without a CEL. I plugged in my scanner after driving to work, and I have a pending code of P2A00 again.

Frustrating to say the least! I'm curious if I shoukd extend my primary o2 a/f sensor to the lower bung on the header like in the older '02-'03 spec v's. Maybe that extra 10" would allow the exhaust gas to cool slightly enough to keep the readings within the parameters the ECM is looking for.

I'm also curious if I didn't mess up my intake air temperature sensor when I a installed my short ram.

Any thoughts?

NissanTech 03-27-2011 12:26 PM

Yes, the P0102 is definitely related to the Idle Learning procedure, but on the step 6 of the procedure it ask you to erase the codes. Just clear the code you will be fine.

Quote:

I'm also curious if I didn't mess up my intake air temperature sensor when I a installed my short ram.
It.s possible but not likely. Try clearing the code first.

Quote:

Frustrating to say the least! I'm curious if I shoukd extend my primary o2 a/f sensor to the lower bung on the header like in the older '02-'03 spec v's. Maybe that extra 10" would allow the exhaust gas to cool slightly enough to keep the readings within the parameters the ECM is looking for.
I never done that but it wouldn't hurt to try.

I had the same problem with a Maxima. We changed all sensors, reprogram ECM, flush injectors, intake, etc. and the code keep coming back. Finally we found a very small hole, about 2 mm in diameter, close to the O2 sensor location, we plug the hole that fixed the problem.

DareDevil 03-28-2011 04:31 PM

I've been looking over the intake and header for any sort of hole, because that's the only thing left that I can imagine it being.

I didn't use any sort of loc-tite or anti seize when I installed the 02 sensors. Do you think oxygen could be squeaking through the threads and skewing the sensor?

NissanTech 03-28-2011 05:29 PM

Quote:

Do you think oxygen could be squeaking through the threads and skewing the sensor?
Very unlikely, I never use loctite either, I only use anti-seize grease. How are the exhaust gaskets?

DareDevil 03-28-2011 07:30 PM

I just replaced the manifold gasket with an OEM Nissan gasket a couple weeks ago. The shop I had install the header used the junk gasket from Megan Racing and it was leaking cylinder 1 & 4. The donut gasket appeared to be in good shape.

DareDevil 03-30-2011 06:02 PM

I took apart my intake today and couldn't find any leaks. I looked over my header as best I could, & no holes I can identify. Does my a/f sensor look like it should after about a year of use?

http://i149.photobucket.com/albums/s...h/13441048.jpg

http://i149.photobucket.com/albums/s...h/9afd2005.jpg

DareDevil 03-31-2011 12:12 PM

I called Henderson Nissanwhere I took my car last time to get that SES diagnosed & smogged. They apparently did an idle air relearn & just drove it for a while to reset the monitors, after which it passed smog. The SES light came back on after about 100 miles. I should have taken it back right then, but I have one of those jobs where I work 10-14 hours per day 6 days a week.

The light came on only after installing the header and I can find nothing else that would cause that SES light. Everything leads back to it! Maybe I should try a different header?

I wish the Nismo catless header wasn't so damn expensive...

mike_s 03-31-2011 04:12 PM

I run the Megan catless header and have had no lights since I installed it. Been about 2 years and 30,000+ miles. I used the anti-fowler extension they provided and their gasket too.

DareDevil 04-02-2011 04:58 PM

Hi Mike,

Based on your signature, it looks like you have a 2003. Your primary O2 is located after the collector on the header, isn't that true?

I believe they changed the '05-'06 to have the O2 built into cylinder #2 only.

I'm going to extend my 02 sensor wires and see if I can relocate my sensor to the lower bung like yours and see if that makes any sort of difference.


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