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Discussion Starter · #1 · (Edited)
I doubt it does matter ... but curiosity hit me ...

After replacing my gas cap (which has been off for months as a result of an experiment for the team) and clearing my SES (using the el cheapo Autel MaxiScan $22 scanner), I received 9 pending codes on my first trip (with concurrent low-idle cold-engine barely discernible misfiring).

While I'll wait a few days to see if any of these end up triggering the SES light, I'm curious about the order the Pcodes were output by the scanner.

Here is the order of the nine pending codes (along with the corresponding description as per this BMW-PCodes thread):

  1. P0306,BMW 243, Cylinder 6 Misfire Detected
  2. P1346,BMW 240, Misfire During Start Cylinder 3
  3. P1343,BMW 238, Misfire Cylinder 1 with Fuel Cut-Off
  4. P1083,BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
  5. P1085,BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
  6. P1349,BMW 241, Misfire Cylinder 4 with Fuel Cut-Off
  7. P1351,BMW 242, Misfire Cylinder 5 with Fuel Cut-Off
  8. P0171,BMW 227, System Too Lean (Bank 1)
  9. P0174,BMW 228, System Too Lean (Bank 2)
Notice, while the order isn't numerical, it 'is' grouped.

Just curious: Does the order presented by the scanner mean anything at all?
 

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It's probably the order in which the codes were read out: LIFO?

Grouping probably indicated that the codes were set together in time.
 

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Discussion Starter · #3 ·
Grouping probably indicated that the codes were set together in time.
That might be it.

There's 'something' to the grouping, whether it's the order the modules are read, or the time the code was set; but it's not purely numerical.

Today, a day later, I now have 3 Pcodes and 1 pending code (where the pending code was listed last):

  1. SES: P1083,BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
  2. SES: P1085,BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
  3. SES: P0174,BMW 228, System Too Lean (Bank 2)
  4. PENDING: P0171,BMW 227, System Too Lean (Bank 1)
Notice the SES-set P0174 code switched order with the P0171 pending code when it moved from pending to setting the SES.
 

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Discussion Starter · #5 · (Edited)
I came here hoping it was a discussion about the high OBC built-in error code readout.
Ooops.

I just changed the title from:
- Just curious: Does the ORDER of pcodes listed in an OBC scanner actually matter?
TO:
- Just curious: Does the ORDER of pcodes listed in an OBDII scanner actually matter?

I'll look at the grouping you referred to.
Meanwhile, the codes morphed into the following, in this order:


SET:

  1. P1083,BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
  2. P1085,BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
  3. P0171,BMW 227, System Too Lean (Bank 1)
  4. P0174,BMW 228, System Too Lean (Bank 2)
PENDING:

  1. P1346,BMW 240, Misfire During Start Cylinder 3
  2. P1343,BMW 238, Misfire Cylinder 1 with Fuel Cut-Off
  3. P1349,BMW 241, Misfire Cylinder 4 with Fuel Cut-Off
  4. P1351,BMW 242, Misfire Cylinder 5 with Fuel Cut-Off
Funny, I didn't 'feel' the fuel shut off.
Anyway, since I had removed & re-installed the DISA valve after reading those codes, I erased them and went for a five mile drive (car was already warm when I started).

The only code that showed up in that 5-mile drive was a pending:

  • P0171,BMW 227, System Too Lean (Bank 1)
I'll read the referenced links to see if there's information in the order. In addition, I might try harder to get a PC going that can become the diagnostic PC with INPA/EDIABAS/NCS/DIS/PROGMAN, etc.
 

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Discussion Starter · #6 · (Edited)
I'm going to try to keep a faithful log of the codes, just in case there is value in the order and occurrence.

For example, after re-clearing the codes, and driving for a couple of days, the following were set in this order:

NOTE: Items in red are new to this sequence.

Also note the P0313 code both set & pending at the same time (which is weird); however also note that P0313 has multiple BMW codes associated with it (i.e., BMW 238, 239, 240, 241, 242, & 243), some of which, e.g., BMW 243, have multiple P-Codes associated in return (e.g., P0313 and P1353 can both be represented by BMW 243).

  • P0313 DTC SET
    • BMW 238 to BMW 243 inclusive, Misfire Detected with Low Fuel
  • P1085 DTC SET
    • BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
  • P0171 DTC SET
    • BMW 227, System Too Lean (Bank 1)
  • P0174 DTC SET
    • BMW 228, System Too Lean (Bank 2)
  • P0313 PENDING
    • BMW 238 to BMW 243 inclusive, Misfire Detected with Low Fuel
  • P1353 PENDING
    • BMW 243, Misfire Cylinder 6 with Fuel Cut-Off
  • P1346 PENDING
    • BMW 240, Misfire During Start Cylinder 3
  • P1343 PENDING
    • BMW 238, Misfire Cylinder 1 with Fuel Cut-Off
  • P1083 PENDING
    • BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
  • P1351 PENDING
    • BMW 242, Misfire Cylinder 5 with Fuel Cut-Off
Then, after clearing and driving for a day or two, they were, in this order:

  • P1083 DTC SET
    • BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
  • P1085 DTC SET
    • BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
  • P0171 DTC SET
    • BMW 227, System Too Lean (Bank 1)
  • P0174 PENDING
    • BMW 228, System Too Lean (Bank 2)
So, this evening, back at home, I cleared the codes, to start the logging analysis anew.

BTW, the car drives fine, as far as I can tell. There is often a very slight stumbling in the morning, after a cold start, and perhaps within the first five or ten minutes; but after an ignition restart, it idles as smooth as silk (or so it seems). Of course, I have a lot of debugging to do ... but ... for now, I'll concentrate on logging the codes to see what pops up and in what order.
 

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Discussion Starter · #7 ·
They're probably grouped, whether by the DME or the scanner, in this order:
That was a valiant guess Quick99Si!

Here's the chart you referred to:


With respect to the order, the following is becoming obvious:

  1. Clearly pending codes are shown AFTER 'thrown' codes ...
  2. Less clearly, some related P-codes seem to be grouped together (e.g., P0171 with P0174, or P1083 with P1085)
  3. However, neither the second digit nor the third digit seems to consistently be in sequence
It 'could' be that this second-digit/third-digit sequence is 'within' another sequence (e.g., by module); but I don't have enough data to support that hypothesis just yet.
 

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Discussion Starter · #8 ·
If it wasn't obvious, looking only at the 'third digit', we see only 3, 0, 1 (mostly, but not always in that order) showing up.

According to the charts, that comprises the following systems:

  • PX3XX === 3 === Ignition or Misfire
  • PX0XX === 0 === SAE Reserved
  • PX1XX === 1 === Emissions Management (Fuel or Air)
I realize these results are not surprising ... but, in the interest of gleaning information from the order, I present what we see.
 

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you might want to look for a vacuum leak or a damaged or cracked boot between the TB and the MAF. that is the most common source of intermittent leans, after that is fuel filter, fuel pump or failing injectors,(however the random nature of the misfires does not support the injector issues) I would also check the fuel rail pressure could be a FPR issue though I think that might be in the pump.
 

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Discussion Starter · #10 · (Edited)
vacuum leak or a damaged or cracked boot between the TB and the MAF.
Thanks for the debugging hint. I haven't actually 'begun' to debug; but when I do, I will look there.

Besides following the misfire diagnostic tree:
- How to diagnose a typical BMW E39 engine misfire (1)

What I 'probably' should do is buy a length of the variously sized vacuum hoses and replace them all, en masse.

To that end, I'll begin a quest to ascertain the sum totals of the finite sizes for all vacuum hoses over in this thread:
- How to locate & replace all the vacuum hoses in the E39 engine bay (1)

after that is fuel filter, fuel pump or failing injectors
I plan on renting the $150 Autozone fuel system tester tool and figuring out how to use it to test my fuel system:
- How do I test fuel pressure?



Meanwhile, the diagnostic trouble codes that appear most frequently (and which are the current codes today), are as follows:

  • P0171, BMW 227, System Too Lean (Bank 1)
  • P0174, BMW 228, System Too Lean (Bank 2
  • P1083, BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
  • P1085, BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
 

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Discussion Starter · #11 ·
For the record, the DTC & pending code order has been rather consistent.

I drove for a few days, without clearing the codes, and this is what I read two days ago, in this order:

Note that some codes (e.g., P0313) are both thrown & pending:

  • DTC:
    • P0313 BMW 238 to BMW 243 inclusive, Misfire Detected with Low Fuel
    • P0300 BMW 62 Random/Multiple Cylinder Misfire Detected
    • P1353 BMW 243, Misfire Cylinder 6 with Fuel Cut-Off
    • P1083 BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
    • P1085 BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
    • P1351 BMW 242, Misfire Cylinder 5 with Fuel Cut-Off
    • P0171 BMW 227, System Too Lean (Bank 1)
    • P0174 BMW 228, System Too Lean (Bank 2)
  • PENDING:
    • P0313 BMW 238 to BMW 243 inclusive, Misfire Detected with Low Fuel
    • P0300 BMW 62 Random/Multiple Cylinder Misfire Detected
After clearing the codes, and driving for a while, the following occurred in this order yesterday:

  • DTC:
    • P0171 BMW 227, System Too Lean (Bank 1)
    • P0174 BMW 228, System Too Lean (Bank 2)
  • PENDING
    • P1083 BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
    • P1085 BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
Again, after clearing them and driving for about twenty miles, the following occurred today, in this order:

  • DTC:
    • P0313 BMW 238 to BMW 243 inclusive, Misfire Detected with Low Fuel
    • P1085 BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
  • PENDING:
    • P0313 BMW 238 to BMW 243 inclusive, Misfire Detected with Low Fuel
    • P1083 BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
    • P0171 BMW 227, System Too Lean (Bank 1)
    • P0174 BMW 228, System Too Lean (Bank 2)
Clearing yet again, and driving for a dozen additional miles, I found, in this order when I shut the engine down to look for vacuum leaks:

  • DTC
    • P0313 BMW 238 to BMW 243 inclusive, Misfire Detected with Low Fuel
    • P1085 BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
    • P0171 BMW 227, System Too Lean (Bank 1)
    • P0174 BMW 228, System Too Lean (Bank 2)
  • PENDING
    • P0313 BMW 238 to BMW 243 inclusive, Misfire Detected with Low Fuel
    • P1083 BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
 

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Discussion Starter · #12 · (Edited)
Not surprisingly, when I tested the DISA valve today:
- Strange results from a simple test of the M54 DISA valve today

I got a pending DISA-related code:

  • P1512 BMW 124 DISA (Differentiated Intake Manifold) Control Circuit Signal Low
But, after clearing that, and replacing the front hose #4 of the SAS valve & the two hoses of the F connector & the SAS vacuum end-cap #9 as described here:
- M54 vacuum hoses ... what diameter ... what brand ... what material ... what length?

After replacing & fixing 5 hoses, the codes then morphed to the following, in order:

  • SET:
    • P0313 BMW 238 to BMW 243 inclusive, Misfire Detected with Low Fuel
    • P0171 BMW 227, System Too Lean (Bank 1)
    • P0174 BMW 228, System Too Lean (Bank 2)
  • PENDING:
    • P0313 BMW 238 to BMW 243 inclusive, Misfire Detected with Low Fuel
    • P1346 BMW 240, Misfire During Start Cylinder 3
    • P1343 BMW 238, Misfire Cylinder 1 with Fuel Cut-Off
    • P1083 BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
    • P1085 BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
    • P1351 BMW 242, Misfire Cylinder 5 with Fuel Cut-Off
I cleared these & will keep an eye on what happens next.
(Meanwhile I've rented the fuel system test tool from Autozone).
 

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Discussion Starter · #13 · (Edited)
This is weird ... but ... after replacing a few (not all) of the vacuum hoses (just the one SAS valve hose, plus the two F-connector hoses) and electrical taping over what looks like a crack in the bottom section of the intake boot hose, the quickness, the number, and the variety of lean condition misfire codes diminished greatly.

When I startedthe car, yesterday it ran fine, until, at some point within the first twenty minutes (or so), it 'threw' two pending codes (in this order):

  • SET:
    • none
  • PENDING:
    • P0171 BMW 227, System Too Lean (Bank 1)
    • P0174 BMW 228, System Too Lean (Bank 2)
Then, during my daily drive around town yesterday (about 60 miles in varying conditions), it finally threw a "full" code triggering the SES light.

The subsequent codes read (in this order):

  • SET:
    • P0171, BMW 227, System Too Lean (Bank 1)
  • PENDING:
    • P1353, BMW 243, Misfire Cylinder 6 with Fuel Cut-Off
    • P1349, BMW 241, Misfire Cylinder 4 with Fuel Cut-Off
    • P1351, BMW 242, Misfire Cylinder 5 with Fuel Cut-Off
BTW, I always simply 'assumed' the first three cylinders in front were bank 1 while the last three in the rear were bank 2; but this is seemingly inconsistent with the results above which implies the first bank is lean but the second bank is misfiring.
 

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Discussion Starter · #14 · (Edited)
UPDATE:

I've been kind'a ignoring the actual codes lately, as I researched all the places the vacuum could be leaking and fuel could be starving.

But, today I decided to check, after weeks of not checking, and here, for the record, is what I have (in this order):

  • SET:
    • P0313 BMW 238 to BMW 243 inclusive, Misfire Detected with Low Fuel
    • P0300 BMW 62 Random/Multiple Cylinder Misfire Detected
    • P1083 BMW 202, Fuel Control Limit Mixture Too Lean (Bank 1 Sensor 1)
    • P1085 BMW 203, Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
    • P1349 BMW 241, Misfire Cylinder 4 with Fuel Cut-Off
    • P1351 BMW 242, Misfire Cylinder 5 with Fuel Cut-Off
    • P0171 BMW 227, System Too Lean (Bank 1)
    • P0174 BMW 228, System Too Lean (Bank 2)
  • PENDING:
    • P0313 BMW 238 to BMW 243 inclusive, Misfire Detected with Low Fuel
    • P0300 BMW 62 Random/Multiple Cylinder Misfire Detected
I cleared them, and will see what pops up first again.

Given:
Bank 2 is cylinder 4, 5, and 6. Those are the rearmost 3 cylinders.
Bank 2 sensor 1 is the pre-cat O2 sensor for the rear 3 cylinders.
I'm going to look up why one oxygen sensor reports on both the front bank1 and the rear bank2 sets of cylinders (I had initially thought there were two oxygen sensors, pre cat).
 

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Discussion Starter · #16 · (Edited)
each bank has two sensors
Now that's interesting.

I had always figured there were two pre-cat and two post-cat oxygen sensors.

But, that diagram appears to show four pre-cat oxygen sensors (two on each bank, the front three being bank one).

I'll try to figure out which is 'sensor 1' out of those two sensors ... and why it's only 'sensor 1' that reports lean conditions in my case.

The four (something) sensors appear to be in this diagram:

How do I know 'which' of these sensors is the one indicated by "bank #1 sensor #1" and "bank #2 sensor #1)?


 

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There are only 4 sensors - 2 pre-cat, 2-post-cat. The regulating sensor is read by the ECU to adjust the fuel injected into the engine, The monitoring sensor monitors catalytic converter performance. The diagram does not identify the catalyst, but it is the bulge downstream of where the there header pipes join. It is part of the exhaust manifold assembly. Check the diagram under engine, exhaust manifold with catalyst.
 

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Discussion Starter · #18 ·
There are only 4 sensors - 2 pre-cat, 2-post-cat
Ah, that simple clarification explains for me which is the sensor 1 of banks 1 and 2.

Thanks for taking the time & courtesy to edify.

Here is my picture edited by you and then cleaned up by me so that others will benefit from the information in the future, long after we're gone.

 

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Discussion Starter · #19 · (Edited)
This post today is the first suggestion that indicates that the order 'does' matter!
- E39 (1997 - 2003) > $1,000 later, SES still on dont know what to do..

Yes it does matter because one problem may cause another which could be eliminated by solving the first.. example if the engine is misfiring and u have a bad 02 sensor, the 02 sensor code might come up first and fixing it could get rid of the misfires so u start from top to bottom
And, this has a good description of the P0171 & P0174 error codes:
- E39 (1997 - 2003) > Not sure if this is in the best of links
 

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Discussion Starter · #20 · (Edited)
I haven't posted in a while so I apologize that I should have updated this thread looong ago.

The causes of the huge plethora of lean-condition codes were only found when I built a smoke machine:
- How to make your own smoke machine (1)

I ended up finding smoke pouring out of the lower CCV hose and out of the upper elbow connected to the ICV valve.




Replacing those and running the FTP, wiped out the DTCs!
- How to better understand the key EPA federal test procedure (FTP) concept of the BMW SES "drive cycle" (1)

After fixing a dozen lean-condition misfire codes, here are my latest California smog emissions test results at an inspection-only station (the California government is so badly managed that they make you pay more every few years for your inspection just so they can watch over their inspection stations instead of actually watching over their inspection stations).



Comparing old, to new (same vehicle) over time ...
--------------------------------------
- Northern California (bluebee), 2002 525i, 87 AKI (just after rebuilding the ABS control module)
- Northern California (bluebee), 2002 525i, 91 AKI (after clearing P0500 code & driving for two weeks)
- Northern California (bluebee), 2002 525i, 87 AKI (two years later)
--------------------------------------
HYDROCARBONS:
- 15mph (2400 rpm): bluebee: 0 ppm (limit = 52 ppm, avg = 4 ppm), 87AKI, PASS
- 15mph (2445 rpm): bluebee: 9 ppm (limit = 52 ppm, avg = 4 ppm), 91AKI (worse than 87AKI), PASS
- 15mph (1914 rpm): bluebee: 2 ppm (limit = 51 ppm, avg = 4 ppm), test results two years later, PASS

- 25mph (2400 rpm): bluebee: 0 ppm (limit = 36 ppm, avg = 4 ppm), 87AKI, PASS
- 25mph (2393 rpm): bluebee: 2 ppm (limit = 36 ppm, avg = 4 ppm), 91AKI (worse than 87AKI), PASS
- 25mph (1331 rpm): bluebee: 2 ppm (limit = 35 ppm, avg = 4 ppm), test results two years later, PASS
--------------------------------------
Carbon Monoxide:
- 15mph (2400 rpm): bluebee: 0.00% (limit = 0.49%, avg = 0.01%), 87AKI, PASS
- 15mph (2445 rpm): bluebee: 0.01% (limit = 0.49%, avg = 0.01%), 97AKI (worse than 87AKI), PASS
- 15mph (1914 rpm): bluebee: 0.01% (limit = 0.48%, avg = 0.01%), test results two years later, PASS

- 25mph (2400 rpm): bluebee: 0.00% (limit = 0.46%, avg = 0.01%), 87AKI, PASS
- 25mph (2393 rpm): bluebee: 0.01% (limit = 0.46%, avg = 0.01%), 97AKI (worse than 87AKI), PASS
- 25mph (1331 rpm): bluebee: 0.01% (limit = 0.46%, avg = 0.01%), test results two years later, PASS
--------------------------------------
Nitrogen Oxides:
- 15mph (2400 rpm): bluebee: 21 ppm (limit = 424 ppm, avg = 16 ppm), 87AKI, PASS
- 15mph (2445 rpm): bluebee: 53 ppm (limit = 424 ppm, avg = 16 ppm), 91AKI (worse than 87AKI), PASS
- 15mph (1914 rpm): bluebee: 56 ppm (limit = 419 ppm, avg = 27 ppm), test results two years later, PASS

- 25mph (2400 rpm): bluebee: 25 ppm (limit = 711 ppm, avg = 18 ppm), 87AKI, PASS
- 25mph (2393 rpm): bluebee: 63 ppm (limit = 711 ppm, avg = 18 ppm), 91AKI (worse than 87AKI), PASS
- 25mph (1331 rpm): bluebee: 285 ppm (limit = 706 ppm, avg = 26 ppm), test results two years later, PASS
--------------------------------------
Carbon Dioxide:
- 15mph (2400 rpm): bluebee: 15.0% (no limit provided), 87AKI
- 15mph (2445 rpm): bluebee: 15.1% (no limit provided), 91AKI (worse than 87AKI)
- 15mph (1914 rpm): bluebee: 14.8% (no limit provided), test results two years later

- 25mph (2400 rpm): bluebee: 15.0% (no limit provided), 87AKI
- 25mph (2393 rpm): bluebee: 15.1% (no limit provided), 91AKI (worse than 87AKI)
- 25mph (1331 rpm): bluebee: 14.9% (no limit provided), test results two years later
--------------------------------------
Oxygen:
- 15mph (2400 rpm): bluebee: 0.0% (no limit provided), 87AKI
- 15mph (2445 rpm): bluebee: 0.0% (no limit provided), 91AKI
- 15mph (1914 rpm): bluebee: 0.0% (no limit provided), test results two years later

- 25mph (2400 rpm): bluebee: 0.0% (no limit provided), 87AKI
- 25mph (2393 rpm): bluebee: 0.0% (no limit provided), 91AKI
- 25mph (1331 rpm): bluebee: 0.0% (no limit provided), test results two years later
--------------------------------------

Interestingly, over the two years, only the nitrogen oxides jumped appreciably. But why?
 

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