O2 sensor responsible for P0171?

[M_Bimmer]

Originally Posted by 750iClown

Much thanks for that. I thought the Lambda ending in 100 was one of the pre-cat (bank 2), and 101 was bank 1. Glad you clarified. I'm thinking of just doing the two pre-cat sensors (11787935100), then see if that fixes the problem. Next, if that doesn't fix it, then do the left and right Manifold Pressure sensors, then the intake temp sensor, and last the 2 post-cat sensors.

Before ordering parts from your favorite BMW source, please ensure the part numbers I supplied are correct:

1. Hyperlink to intake temperature sensor: https://www.bmw-etk.info/parts-catal...08/13/13_2173/
   
2. Hyperlink to lambda sensors: https://www.bmw-etk.info/parts-catal...08/18/18_1188/
   
3. Hyperlink to manifold pressure sensor: https://www.bmw-etk.info/parts-catal...08/11/11_7361/

[Raimo5]

Hey look, bmw-etk.info is back online!

[750iClown]

Originally Posted by M_Bimmer

.

I have the pre cat sensor coming in the mail. Which one is the bank 1 sensor? Is it the passenger side one (your left red arrow) or the one closer to driver's side?

[Raimo5]

Originally Posted by 750iClown

I have the pre cat sensor coming in the mail. Which one is the bank 1 sensor? Is it the passenger side one (your left red arrow) or the one closer to driver's side?

It would be the passenger side bank on the left hand drive car like yours.

[750iClown]

Originally Posted by Raimo5

It would be the passenger side bank on the left hand drive car like yours.

Thanks, i am seeing several others confirming that when googling that question.

[750iClown]

Originally Posted by Raimo5

It would be the passenger side bank on the left hand drive car like yours.

I replaced it a few minutes ago. Been running it in the garage for several minutes, but expectedly the CEL is still lit. What are your recommendations to see if it worked? Driving is not an option at this point as the weather is terrible (salt and chemicals on the road and it's snowing). Should I clear the code w OBD2 or ISTA? If so, then what?

[Raimo5]

Clear the codes and run it to see if it is actually the same CEL trigger code that comes back up.

[750iClown]

Originally Posted by Raimo5

Clear the codes and run it to see if it is actually the same CEL trigger code that comes back up.

Will do. In order to see the trigger code what would happen? CEL comes back? CEL took a while to come back when I cleared it before, so I'm assuming a trigger code is something else?

[750iClown]

Originally Posted by Raimo5

Clear the codes and run it to see if it is actually the same CEL trigger code that comes back up.

Same code came back, mixture adaptation (fuel-air mixture too lean), but there's also this "energy diagnosis", or "power management: Remote software upgrade deactivated due to aging battery". So I am wondering if I should start with getting a new battery and throwing it in there, I am going to return this. 02 sensor and use that money toward a new battery.

[750iClown]

I can't find my voltage tester. Before I go out and buy a new battery I'm going to test the voltage on this one.

[Raimo5]

Pretty sure that battery is not an issue here as it is only a safeguard measure not to strain potentially old battery. I think that this entry only takes into account battery registration date. You can run service module "energy diagnosis" to see what is says there.

There arent too many scenarios that can drive turbo engine lean. Usually if there is an intake leak then you would end up with rich mixture issues as intake is pressurised not under vacuum like naturally aspirated engines. If electronic probes check out, and I'm not saying they do, then I would suspect fuel delivery.

You need to play around with ISTA and live data to see where exactly is the discrepancy stemming from.

[750iClown]

Originally Posted by Raimo5

Pretty sure that battery is not an issue here as it is only a safeguard measure not to strain potentially old battery. I think that this entry only takes into account battery registration date. You can run service module "energy diagnosis" to see what is says there.

There arent too many scenarios that can drive turbo engine lean. Usually if there is an intake leak then you would end up with rich mixture issues as intake is pressurised not under vacuum like naturally aspirated engines. If electronic probes check out, and I'm not saying they do, then I would suspect fuel delivery.

You need to play around with ISTA and live data to see where exactly is the discrepancy stemming from.

What you said there makes total sense. I've been wondering if it is 1 or more fuel injectors in bank 1. Since this is not happening in bank 2 it would seem that this is not a fuel pump or fuel delivery issue at a source that occurs prior to arriving at the engine. Thoughts? I hear you on the battery. I'm getting a voltage meter this weekend to check on that.

[Raimo5]

Originally Posted by 750iClown

What you said there makes total sense. I've been wondering if it is 1 or more fuel injectors in bank 1. Since this is not happening in bank 2 it would seem that this is not a fuel pump or fuel delivery issue at a source that occurs prior to arriving at the engine. Thoughts? I hear you on the battery. I'm getting a voltage meter this weekend to check on that.

Bank 2 might also be affected if low pressure pump is weak, but still within tolerances not to throw an error. Bare in mind that you have one low pressure pump inside the fuel tank, but two different cam driven high pressure pumps, both operated by their respective banks and feeding separate fuel rails. You should check the low and high pressure values to see if they are within nominal range.

If low pressure and high pressure systems are operating within normal pressures across the whole power band (not just idling!), then pressure buildup systems are not the issue.

You can narrow your search considerably by making sure that sensors are showing right data. If you find one that doesn't look right, then you can go upstream from there. There is also Expert Mode in ISTA which can plot and record different values when vehicle is driven.

[750iClown]

Originally Posted by Raimo5

Bank 2 might also be affected if low pressure pump is weak, but still within tolerances not to throw an error. Bare in mind that you have one low pressure pump inside the fuel tank, but two different cam driven high pressure pumps, both operated by their respective banks and feeding separate fuel rails. You should check the low and high pressure values to see if they are within nominal range.

If low pressure and high pressure systems are operating within normal pressures across the whole power band (not just idling!), then pressure buildup systems are not the issue.

You can narrow your search considerably by making sure that sensors are showing right data. If you find one that doesn't look right, then you can go upstream from there. There is also Expert Mode in ISTA which can plot and record different values when vehicle is driven.

I really need a tutorial on where to start with testing/checking live data for all these respective sensors. I guess I can start by googling ISTA and relevant search terms like data, or values or something. Do you have any recommendations for that?

This video was something I saw previously, and was also posted by someone else here, maybe you. I guess I can check the lambda's by searching "lambda", and also search other relevant parts that I need to test like maybe the fuel injectors and such. Maybe you can help me put a list together for values I can test.

[Raimo5]

Originally Posted by 750iClown

I really need a tutorial on where to start with testing/checking live data for all these respective sensors. I guess I can start by googling ISTA and relevant search terms like data, or values or something. Do you have any recommendations for that?

This video was something I saw previously, and was also posted by someone else here, maybe you. I guess I can check the lambda's by searching "lambda", and also search other relevant parts that I need to test like maybe the fuel injectors and such. Maybe you can help me put a list together for values I can test.

My advice - get to know your engine. If you like to work on your car and are planning to do so in the future then it is best to get well acquainted. Here is a link with N63 technical training pdf. I feel that reading through this is needed if you want to understand what you are doing and progress on your own with diagnosis. It will also give context to everything you see in ISTA. Data on its own if worthless. You also need insight so all that data makes sense and you could make well informed decisions and diagnosis.

If you really want to to proper job about it then I would advise to read that document and then put aside some 5 hours of your time and spend it on sitting in your car and just playing around with ISTA, seeing all its functions and what it can do. There are no free lunches in this world and if you dont want to pay the mechanic then you have to pay with your own time to get to know the engine you are working on and then work on it. I'm here to help, but I can only provide approximate guidance as I dont have your engine, so ECU specific functions and values are somewhat different to yours and not cross compatible for comparison. Other than teleconferencing the diagnostics session, that is the best I can do.

Now that you are N63 guru, let's get to troubleshooting. I would start with looking all the sensor data values. MAF, intake air temps, intake manifold pressures, exhaust pressures and temperatures, fuel pressures, cylinder combustion pressures, O2 sensors, cam and crank position sensors. Basically I would check all electronic feedback against known good values because that requires zero disassembly and will narrow down or even pinpoint your area of diagnosis. You even have two banks, with one presumably running correct, which makes for a good data reference point.

If you find a probe that reports data outside of what it should or is otherwise anomalous, then your issue is likely upstream from that probe, or the probe itself. Again, search narrowed.

If everything on the sensor side checks out then I would go on by extracting the injectors and send them to testing and cleaning. While at it, I would do cylinder compression and leakdown tests to rule out any compression losses and leaky valves. Water in intake, rust on valve collars, lean running ...... you know, anything is possible so we have to work with what we find. Also as part of mechanical diagnosis I would do smoke test on intake and exhaust run to make sure all is good there. Of course also inspect the spark plugs to see what story they tell and which cylinders run bad. Perhaps get a good look of intake runs with borescope, clean the valves if necessary.

At that point, you should have your problem well covered. If not then .... well, lets get to it when we get to it.

[750iClown]

Originally Posted by Raimo5

My advice - get to know your engine. If you like to work on your car and are planning to do so in the future then it is best to get well acquainted. Here is a link with N63 technical training pdf. I feel that reading through this is needed if you want to understand what you are doing and progress on your own with diagnosis. It will also give context to everything you see in ISTA. Data on its own if worthless. You also need insight so all that data makes sense and you could make well informed decisions and diagnosis.

If you really want to to proper job about it then I would advise to read that document and then put aside some 5 hours of your time and spend it on sitting in your car and just playing around with ISTA, seeing all its functions and what it can do. There are no free lunches in this world and if you dont want to pay the mechanic then you have to pay with your own time to get to know the engine you are working on and then work on it. I'm here to help, but I can only provide approximate guidance as I dont have your engine, so ECU specific functions and values are somewhat different to yours and not cross compatible for comparison. Other than teleconferencing the diagnostics session, that is the best I can do.

Now that you are N63 guru, let's get to troubleshooting. I would start with looking all the sensor data values. MAF, intake air temps, intake manifold pressures, exhaust pressures and temperatures, fuel pressures, cylinder combustion pressures, O2 sensors, cam and crank position sensors. Basically I would check all electronic feedback against known good values because that requires zero disassembly and will narrow down or even pinpoint your area of diagnosis. You even have two banks, with one presumably running correct, which makes for a good data reference point.

If you find a probe that reports data outside of what it should or is otherwise anomalous, then your issue is likely upstream from that probe, or the probe itself. Again, search narrowed.

If everything on the sensor side checks out then I would go on by extracting the injectors and send them to testing and cleaning. While at it, I would do cylinder compression and leakdown tests to rule out any compression losses and leaky valves. Water in intake, rust on valve collars, lean running ...... you know, anything is possible so we have to work with what we find. Also as part of mechanical diagnosis I would do smoke test on intake and exhaust run to make sure all is good there. Of course also inspect the spark plugs to see what story they tell and which cylinders run bad. Perhaps get a good look of intake runs with borescope, clean the valves if necessary.

At that point, you should have your problem well covered. If not then .... well, lets get to it when we get to it.

With it being a little warmer out and in my garage I ran tests today. Interestingly ISTA saying the ODB2 code is P0174, not P0171. I ran all the tests on the O2 sensors and they all checked out ok. I also had the Tank Vent Valve checked and that was fine. I'm starting to wonder if I have an air leak somewhere and need to do a smoke test.

I need to find where ilI can test all those other items you mentioned. I only ran the tests available to me as part of the "Mixture Adaptation" test plan. Maybe I'll need to specifically search out the tests for all those items you mentioned. For example, I saw a video where the person searched up "lambda" in text search, and then ran the O2 sensor tests to get those readings. Thoughts?

[Raimo5]

Originally Posted by 750iClown

With it being a little warmer out and in my garage I ran tests today. Interestingly ISTA saying the ODB2 code is P0174, not P0171. I ran all the tests on the O2 sensors and they all checked out ok. I also had the Tank Vent Valve checked and that was fine. I'm starting to wonder if I have an air leak somewhere and need to do a smoke test.

I need to find where ilI can test all those other items you mentioned. I only ran the tests available to me as part of the "Mixture Adaptation" test plan. Maybe I'll need to specifically search out the tests for all those items you mentioned. For example, I saw a video where the person searched up "lambda" in text search, and then ran the O2 sensor tests to get those readings. Thoughts?

In ISTA, you can find service functions by using information search or service functions in vehicle management tab. You can also call up ECU functions from ECU tree and there are loads of values to be obtained from there.

[M_Bimmer]

Originally Posted by 750iClown

With it being a little warmer out and in my garage I ran tests today. Interestingly ISTA saying the ODB2 code is P0174, not P0171. I ran all the tests on the O2 sensors and they all checked out ok. I also had the Tank Vent Valve checked and that was fine. I'm starting to wonder if I have an air leak somewhere and need to do a smoke test.

I need to find where ilI can test all those other items you mentioned. I only ran the tests available to me as part of the "Mixture Adaptation" test plan. Maybe I'll need to specifically search out the tests for all those items you mentioned. For example, I saw a video where the person searched up "lambda" in text search, and then ran the O2 sensor tests to get those readings. Thoughts?

Out of curiosity, what does ISTA's Test Plan spell out for your specific code?

Someone just posted a screen shot asking what to do next in ISTA, and the screenshot actually stated the next troubleshooting steps.

The power of ISTA is the Test Plans for each code (and the wiring diagrams).

[750iClown]

Originally Posted by M_Bimmer

Out of curiosity, what does ISTA's Test Plan spell out for your specific code?

Someone just posted a screen shot asking what to do next in ISTA, and the screenshot actually stated the next troubleshooting steps.

The power of ISTA is the Test Plans for each code (and the wiring diagrams).

I did the test plan. One of the tests was the lambda sensors but they all tested fine. Another big part of the testing is the smoke test for air leaks. I bought a nice smoke tester off ebay yesterday for half price. I want to run tests on other sensors and items on the vehicle in the meantime, so I'm going to look at the list of items Raimo mentioned and see what I can test in that list. Thoughts?

[M_Bimmer]

Originally Posted by 750iClown

I did the test plan. One of the tests was the lambda sensors but they all tested fine. Another big part of the testing is the smoke test for air leaks. I bought a nice smoke tester off ebay yesterday for half price. I want to run tests on other sensors and items on the vehicle in the meantime, so I'm going to look at the list of items Raimo mentioned and see what I can test in that list. Thoughts?

Once you find the root cause, you'll have educated us all.

Keep us posted...

[750iClown]

Originally Posted by M_Bimmer

Once you find the root cause, you'll have educated us all.

Keep us posted...

This is really interesting. Ok now i haven't had time to do additional testing as I've been very busy. I also did not hook up my charger during attempts to run items in the ISTA test plan (charger required during certain tests to read out sensor information), as the charger was at my parent's house. I plan to do a smoke test tonight as I ordered a Solary smoke tester off ebay and it arrived here Friday. The interesting thing I noticed.... I recently posted after installing the new O2 sensor on bank 1 that the CEL came back up again, HOWEVER, this time it is a P0174 (bank 2), instead of P0171. VERY VERY strange. So at this point I'm going to swap out the O2 sensor on bank 2 with the O2 sensor I removed from bank 1 and see what happens. If I'm still coding, then I'm very inclined to think that both previous O2 sensors may need to be replaced.

Before I do that however, I'm going to do a smoke test on both banks. Thoughts?

[M_Bimmer]

Originally Posted by 750iClown

This is really interesting. Ok now i haven't had time to do additional testing as I've been very busy. I also did not hook up my charger during attempts to run items in the ISTA test plan (charger required during certain tests to read out sensor information), as the charger was at my parent's house. I plan to do a smoke test tonight as I ordered a Solary smoke tester off ebay and it arrived here Friday. The interesting thing I noticed.... I recently posted after installing the new O2 sensor on bank 1 that the CEL came back up again, HOWEVER, this time it is a P0174 (bank 2), instead of P0171. VERY VERY strange. So at this point I'm going to swap out the O2 sensor on bank 2 with the O2 sensor I removed from bank 1 and see what happens. If I'm still coding, then I'm very inclined to think that both previous O2 sensors may need to be replaced.

Before I do that however, I'm going to do a smoke test on both banks. Thoughts?

Well, sounds like you are back on post #82...

Seriously, I do hope to hear some good news on your issue....