My 2013 altima 2.5L could not start an engine. It turned on P0101 and P2119. After replacing an air filter and cleaning MAF and throttle body, it seemed that everything is fine. However, in the next day, ECM set P0101 again. I replaced MAF filter and PCV valve, but it could not solve my problem.
So, I have taken some experiments for 1 week, in order to confirm what the conditions set P0101 by. I found that ECM set P0101 only when my car starts an engine. ECM has never set confirmed or pending P0101 during driving. There was no exception for more than 10 samples. So, I conclude that there is no drivability issue and my car may need to reprogram the ECU according to TSB from nissan.
But, I don't understand what the reprogramming exactly means and why it resolves the problem. Would you let me know what it means and why it can resolve problem? Before going to the dealer, I want to clearly understand situations.
The followings are my thinking.....
1) If Nissan found the bug in their ECM software, the reprogramming means the update of new ECM software.
Some articles that were posted earlier than 2013 mentioned that the ECM reprogramming is needed to fix the P0101 problem. If the reprogramming means the update of new ECM software that fixes a bug, it means that Nissan already knew their ECM software bug before 2013. Then, why did not they fix the bug in 2013-2015 models? According to the TSB, even 2015 model is needed to be reprogramming. It does not make sense. So, I think that the reprogramming is not the update of new ECM software that fixes the bug. The reprogramming may simply reinstall the same ECU software.
2) Although all hardware problems are fixed, why does the ECM turn on P0101?
A Software always throw the same results if the input to the software is same. Fixing all the hardware problems is to going back to the normal hardware conditions. If the ECU sets CEL based on only hardware-driven data, the ECM should not turn on the CEL. However, it still turns on the CEL. It means that ECU software sets the P0101 DTC by refering hardware-driven data as well as some software-driven parameters that do not go back to the normal condition. Although all the hardware problems are fixed, the internal software-driven parameters cannot be changed. For example, ECM reset does not clear the historical faults records. So, these parameters are needed to be cleared, and the reprogramming maybe means that it clears every parameters in ECM.
3) whatever there is a bug or not in old ECM software,
Old ECM software worked fine before the problem started. If the CEL problem cannot be solved by fixing hardware, I believe that some internal software parameters do not go back to the normal values. I don't know what they are, but it could be historical faults. For example, if the ECM found a previous fault of P0101, the ECM might strictly check the regarding sensing data with very small amount of margin. I want to see what happens after clearing the historical faults. In order to clear the historical fault of P0101, I am clearing the pending P0101 DTC, before it prompts to confirmed DTC. After I will clear the historical faults of P0101, let me see what happens.
So, I have taken some experiments for 1 week, in order to confirm what the conditions set P0101 by. I found that ECM set P0101 only when my car starts an engine. ECM has never set confirmed or pending P0101 during driving. There was no exception for more than 10 samples. So, I conclude that there is no drivability issue and my car may need to reprogram the ECU according to TSB from nissan.
But, I don't understand what the reprogramming exactly means and why it resolves the problem. Would you let me know what it means and why it can resolve problem? Before going to the dealer, I want to clearly understand situations.
The followings are my thinking.....
1) If Nissan found the bug in their ECM software, the reprogramming means the update of new ECM software.
Some articles that were posted earlier than 2013 mentioned that the ECM reprogramming is needed to fix the P0101 problem. If the reprogramming means the update of new ECM software that fixes a bug, it means that Nissan already knew their ECM software bug before 2013. Then, why did not they fix the bug in 2013-2015 models? According to the TSB, even 2015 model is needed to be reprogramming. It does not make sense. So, I think that the reprogramming is not the update of new ECM software that fixes the bug. The reprogramming may simply reinstall the same ECU software.
2) Although all hardware problems are fixed, why does the ECM turn on P0101?
A Software always throw the same results if the input to the software is same. Fixing all the hardware problems is to going back to the normal hardware conditions. If the ECU sets CEL based on only hardware-driven data, the ECM should not turn on the CEL. However, it still turns on the CEL. It means that ECU software sets the P0101 DTC by refering hardware-driven data as well as some software-driven parameters that do not go back to the normal condition. Although all the hardware problems are fixed, the internal software-driven parameters cannot be changed. For example, ECM reset does not clear the historical faults records. So, these parameters are needed to be cleared, and the reprogramming maybe means that it clears every parameters in ECM.
3) whatever there is a bug or not in old ECM software,
Old ECM software worked fine before the problem started. If the CEL problem cannot be solved by fixing hardware, I believe that some internal software parameters do not go back to the normal values. I don't know what they are, but it could be historical faults. For example, if the ECM found a previous fault of P0101, the ECM might strictly check the regarding sensing data with very small amount of margin. I want to see what happens after clearing the historical faults. In order to clear the historical fault of P0101, I am clearing the pending P0101 DTC, before it prompts to confirmed DTC. After I will clear the historical faults of P0101, let me see what happens.
