P2626 - I've run out of ideas

[bmwlover0725]

My light came on a day after my inspection (thank God) for P2626. ISTA pulls nothing more than this as well. I've thrown two oxygen sensors at it, both of which work and set monitors and then get killed with this code. I don't want to keep throwing them in and I was wondering if it's a fuel injection issue because the car starts extremely hard overnight and seems like there may be excess fuel trying to be burnt there. Just my idea anyway. If anyone could help here it would be greatly appreciated.

[dpaul]

Originally Posted by bmwlover0725

My light came on a day after my inspection (thank God) for P2626. ISTA pulls nothing more than this as well. I've thrown two oxygen sensors at it, both of which work and set monitors and then get killed with this code. I don't want to keep throwing them in and I was wondering if it's a fuel injection issue because the car starts extremely hard overnight and seems like there may be excess fuel trying to be burnt there. Just my idea anyway. If anyone could help here it would be greatly appreciated.

FWIW P-codes are generic. If you've got ISTA installed it should be giving you a BMW hex code. The BMW codes may be no more enlightening than the OBDII codes but at least they are manufacturer-specific. So always report them both.

Furthermore, a freeze-frame of relevant data at the time the error code was set is available in your DME. I don't use ISTA much so I cannot tell you how to get it from ISTA but it's pretty simple with INPA. Figure out how to get it and post it.

Finally, it is always helpful to have a little more history than you've provided. For example, is your car stock or do you have a tune, test pipes etc. Any other symptoms, particularly, decreased fuel economy, black or white smoke on accel/decel, more carbon on exhaust tips than usual etc. How much oil are you using? You've replaced the o2 sensors twice? So you're on your third set? How long in between changes for the code to appear?

All that said, the most common explanations for P2626 are:
Bad sensor (or wire or connector)
Vacuum leak
Exhaust leak

Yes, there are more subtle explanations for your O2 code but those are the big three.

1) You've replaced the sensor twice - this is very unlikely to be a sensor problem. Of course, it's easy enough to test with a voltmeter and a propane torch. But wiring and connectors are often problematic.

2) You have a problem starting - could be unrelated but is consistent with vacuum leak. I'd expect idle issues as well if this were the case.

More precisely tell us why to you think "it seems like there may be excess fuel trying to be burnt there".

[bmwlover0725]

Originally Posted by dpaul

FWIW P-codes are generic. If you've got ISTA installed it should be giving you a BMW hex code. The BMW codes may be no more enlightening than the OBDII codes but at least they are manufacturer-specific. So always report them both.

Furthermore, a freeze-frame of relevant data at the time the error code was set is available in your DME. I don't use ISTA much so I cannot tell you how to get it from ISTA but it's pretty simple with INPA. Figure out how to get it and post it.

Finally, it is always helpful to have a little more history than you've provided. For example, is your car stock or do you have a tune, test pipes etc. Any other symptoms, particularly, decreased fuel economy, black or white smoke on accel/decel, more carbon on exhaust tips than usual etc. How much oil are you using? You've replaced the o2 sensors twice? So you're on your third set? How long in between changes for the code to appear?

All that said, the most common explanations for P2626 are:
Bad sensor (or wire or connector)
Vacuum leak
Exhaust leak

Yes, there are more subtle explanations for your O2 code but those are the big three.

1) You've replaced the sensor twice - this is very unlikely to be a sensor problem. Of course, it's easy enough to test with a voltmeter and a propane torch. But wiring and connectors are often problematic.

2) You have a problem starting - could be unrelated but is consistent with vacuum leak. I'd expect idle issues as well if this were the case.

More precisely tell us why to you think "it seems like there may be excess fuel trying to be burnt there".

Thank you for the response! The code was 00274A through ISTA. I'm not sure how to do freeze frame through it though so I'll have to figure that out. I'm only guessing fuel injector because of the harder start perhaps thinking that it may have fouled my plugs badly, but I'd assume it would always run rough then.

Vacuum I'm guessing not especially because idle is completely fine. It jumps a bit for 2-3 seconds after the hard start and that's it. It's perfectly smooth after that.

There are also no running issues. The reason I doubt it's an O2 sensor aside from already having done two new ones is that all of the monitors initially set and then it fails a while later. It's inspectable initially which I guess is good, but I definitely want to get this fixed. Perhaps I should look to a vacuum leak, but then why would it only be on one side?

[dpaul]

Originally Posted by bmwlover0725

Thank you for the response! The code was 00274A through ISTA. I'm not sure how to do freeze frame through it though so I'll have to figure that out. I'm only guessing fuel injector because of the harder start perhaps thinking that it may have fouled my plugs badly, but I'd assume it would always run rough then.

Vacuum I'm guessing not especially because idle is completely fine. It jumps a bit for 2-3 seconds after the hard start and that's it. It's perfectly smooth after that.

There are also no running issues. The reason I doubt it's an O2 sensor aside from already having done two new ones is that all of the monitors initially set and then it fails a while later. It's inspectable initially which I guess is good, but I definitely want to get this fixed. Perhaps I should look to a vacuum leak, but then why would it only be on one side?

So one important piece of information you left out - when did the O2 problems start relative to the hard start problem?

Also, who did the O2 sensor replacements? Was the joint between exhaust header and catalytic converter disturbed during that process?

Here's something you can do right now - get under the car and look very carefully at the joint between the exhaust headers and the catalytic converter for bank 1 (passenger side). See if there is any carbon residue or other signs that might be interpreted as a leak. If you're uncertain, compare it to the driver side where sensor function seems to be normal. It doesn't take much of a leak to cause a problem.

[dpaul]

Originally Posted by bmwlover0725

Thank you for the response! The code was 00274A through ISTA. I'm not sure how to do freeze frame through it though so I'll have to figure that out. I'm only guessing fuel injector because of the harder start perhaps thinking that it may have fouled my plugs badly, but I'd assume it would always run rough then.

Vacuum I'm guessing not especially because idle is completely fine. It jumps a bit for 2-3 seconds after the hard start and that's it. It's perfectly smooth after that.

There are also no running issues. The reason I doubt it's an O2 sensor aside from already having done two new ones is that all of the monitors initially set and then it fails a while later. It's inspectable initially which I guess is good, but I definitely want to get this fixed. Perhaps I should look to a vacuum leak, but then why would it only be on one side?

Question 1) when did the O2 problems start relative to the hard start problem?

Question 2) who did the O2 sensor replacements? Was the joint between exhaust header and catalytic converter disturbed during that process?

Here's something you can do right now - get under the car and look very carefully at the joint between the exhaust headers and the catalytic converter for bank 1 (passenger side). See if there is any carbon residue or other signs that might be interpreted as a leak. If you're uncertain, compare it to the driver side where sensor function seems to be normal. It doesn't take much of a leak to cause a problem.

While you're under there, carefully inspect the condition of the wires and connector. Often you can't tell a thing but sometimes a problem is obvious.

[bmwlover0725]

Originally Posted by dpaul

Question 1) when did the O2 problems start relative to the hard start problem?

Question 2) who did the O2 sensor replacements? Was the joint between exhaust header and catalytic converter disturbed during that process?

Here's something you can do right now - get under the car and look very carefully at the joint between the exhaust headers and the catalytic converter for bank 1 (passenger side). See if there is any carbon residue or other signs that might be interpreted as a leak. If you're uncertain, compare it to the driver side where sensor function seems to be normal. It doesn't take much of a leak to cause a problem.

While you're under there, carefully inspect the condition of the wires and connector. Often you can't tell a thing but sometimes a problem is obvious.

One thing I also left out, I have no cats and a BPM tune. There are no leaks whatsoever after thoroughly checking though. My guess on wiring is that it's completely fine given that every sets fine at first until the O2 sensor goes bad.

[dpaul]

I understand that you feel there are no exhaust leaks but I have to ask why you are so sure. How exactly did you test for this? Did you personally get up close and personal with your exhaust system?

Having test pipes increases the likelihood of exhaust leaks being the source of your problem. I've personally encountered this issue. The leak was barely detectable. New gasket solved the problem.

Finally, what's the timeline - tune, test pipes, replacement of O2 sensors, appearance of O2 codes, appearance of hardstarting.

[bmwlover0725]

Originally Posted by dpaul

I understand that you feel there are no exhaust leaks but I have to ask why you are so sure. How exactly did you test for this? Did you personally get up close and personal with your exhaust system?

Having test pipes increases the likelihood of exhaust leaks being the source of your problem. I've personally encountered this issue. The leak was barely detectable. New gasket solved the problem.

Finally, what's the timeline - tune, test pipes, replacement of O2 sensors, appearance of O2 codes, appearance of hardstarting.

I appreciate the ongoing help here man, I really do!

So, as far as the exhaust goes - my trans and flywheel clutch assembly all that was replaced recently. This problem started happening over a week before though. I've traced wires to be sure, but I doubt that would be it anyway given that it works for a while and then fails. As far as exhaust goes, same thing... came out when tranny was replaced and has all new gaskets as well. I've also looked for leaks to be sure, but like I said this started happening before that job anyway.

Timeline of the tune dates back about 4 years (BPM) and same with test pipes. O2 sensors were new back then as well. This problem occurs on bank 1 only. Changes sensors fouls out the bank 2 sensors when in bank 1. It goes through one every 150-350 miles I'd say. Lastly, the hard starting just happens when starting from cold and goes away after a few seconds, but it's normally very rough - however it wasn't this morning when I tried to take a video of it

[dpaul]

Originally Posted by bmwlover0725

I appreciate the ongoing help here man, I really do!

So, as far as the exhaust goes - my trans and flywheel clutch assembly all that was replaced recently. This problem started happening over a week before though. I've traced wires to be sure, but I doubt that would be it anyway given that it works for a while and then fails. As far as exhaust goes, same thing... came out when tranny was replaced and has all new gaskets as well. I've also looked for leaks to be sure, but like I said this started happening before that job anyway.

Timeline of the tune dates back about 4 years (BPM) and same with test pipes. O2 sensors were new back then as well. This problem occurs on bank 1 only. Changes sensors fouls out the bank 2 sensors when in bank 1. It goes through one every 150-350 miles I'd say. Lastly, the hard starting just happens when starting from cold and goes away after a few seconds, but it's normally very rough - however it wasn't this morning when I tried to take a video of it

Sorry, I'm still not clear. If you don't mind, be really explicit and linear. Here's a sample timeline - change or add to it if it makes any sense to you

4 yrs ago: tune and test pipes
4 yrs ago: both O2 sensors replaced

5 weeks ago: bank1 O2 sensor code appears

4 weeks ago: exhaust removed and replaced for clutch/flywheel job.

3 weeks ago: bank1 O2 sensor replaced. After 150 miles, code reappears

2 weeks ago: swapped bank1 and bank2 sensors. After 150 miles, code on reappears on bank1. Bank2 OK

1 week ago: bank1 O2 sensor replaced again. After 350 miles, code reappears

Finally, what exactly does this mean:
"Changes sensors fouls out the bank 2 sensors when in bank 1"

[C-los]

if it's happening specifically bank 1,
can you pull the short term and long term fuel trims? thos can help narrow or indicated uneven engine balance, if it's only half the engine, or a general problem, but only one side is being picky.


good luck!

p.s. fuels trims requested while idling.

[bmwlover0725]

Originally Posted by dpaul

Sorry, I'm still not clear. If you don't mind, be really explicit and linear. Here's a sample timeline - change or add to it if it makes any sense to you

4 yrs ago: tune and test pipes
4 yrs ago: both O2 sensors replaced

5 weeks ago: bank1 O2 sensor code appears

4 weeks ago: exhaust removed and replaced for clutch/flywheel job.

3 weeks ago: bank1 O2 sensor replaced. After 150 miles, code reappears

2 weeks ago: swapped bank1 and bank2 sensors. After 150 miles, code on reappears on bank1. Bank2 OK

1 week ago: bank1 O2 sensor replaced again. After 350 miles, code reappears

Finally, what exactly does this mean:
"Changes sensors fouls out the bank 2 sensors when in bank 1"

All of that is correct. The last part just means ruining plugs when I swap a good sensor to the other bad side and it kills it.

Originally Posted by C-los

if it's happening specifically bank 1,
can you pull the short term and long term fuel trims? thos can help narrow or indicated uneven engine balance, if it's only half the engine, or a general problem, but only one side is being picky.


good luck!

p.s. fuels trims requested while idling.

There are the fuel trims! Thanks for looking into it. Unfortunately I accidentally deleted freeze frame data so this is all I have. It shows the freeze frame of the exact second that the problem occurred.

[dpaul]

Originally Posted by bmwlover0725

All of that is correct. The last part just means ruining plugs when I swap a good sensor to the other bad side and it kills it.

There are the fuel trims! Thanks for looking into it. Unfortunately I accidentally deleted freeze frame data so this is all I have. It shows the freeze frame of the exact second that the problem occurred.

FWIW, freeze frame data is still available if you haven't cleared the code yet. However, your trims couldn't be nicer.

I am really sorry but I just cannot seem to understand what you are saying.

Are you saying:
1) start with good sensors in both banks with no codes,
2) see code P2626 in bank 1
3) swap sensors between bank 1 and bank 2
4) Bank 1 codes reappear after driving 150-350 miles but bank 2 remains good, no codes (what I put in the imaginary timetime)

or

4) Bank 1 code appears after driving 150-350 miles but bank 2 codes quickly, indicating the sensor originally in Bank 1 was permanently disabled (NOT what I put in the imaginary timeline).

I'm sorry to be so insistent on this but I think the details might be important. Could you start with my imaginary timeline, read it carefully, edit it so that it reflects reality as much as possible and post it?

[bmwlover0725]

Originally Posted by dpaul

FWIW, freeze frame data is still available if you haven't cleared the code yet. However, your trims couldn't be nicer.

I am really sorry but I just cannot seem to understand what you are saying.

Are you saying:
1) start with good sensors in both banks with no codes,
2) see code P2626 in bank 1
3) swap sensors between bank 1 and bank 2
4) Bank 1 codes reappear after driving 150-350 miles but bank 2 remains good, no codes (what I put in the imaginary timetime)

or

4) Bank 1 code appears after driving 150-350 miles but bank 2 codes quickly, indicating the sensor originally in Bank 1 was permanently disabled (NOT what I put in the imaginary timeline).

I'm sorry to be so insistent on this but I think the details might be important. Could you start with my imaginary timeline, read it carefully, edit it so that it reflects reality as much as possible and post it?

Step 4 of that would be bank one and 2 codes both appear, indicating that the oxygen sensor is being killed each time.

[C-los]

Originally Posted by bmwlover0725

All of that is correct. The last part just means ruining plugs when I swap a good sensor to the other bad side and it kills it.







There are the fuel trims! Thanks for looking into it. Unfortunately I accidentally deleted freeze frame data so this is all I have. It shows the freeze frame of the exact second that the problem occurred.

NP. Fuel Trims aren't bad at all. seems to be leaning out as normal.
Gonna do a bit of research regarding this strange DTC.

I'll get back to this thread.

[Green-Eggs]

Here's the description of 274A from an internal BMW manual. I did the best I could with the formatting. I hope it will make some sense.

274A - P2626

Information saved in DME

Fault code 274A - P2626

Fault text Oxygen sensor pump current calibration fault before cat.
converter, bank 1

Fault description O2 Sensor Pumping Current Trim Circuit/Open (Bank 1
Sensor 1)

Condition for fault identification
Test condition: Oxygen sensor is available, oxygen sensor voltage > 4951
mV (K_LAVK_OBD_SA_DIAG_OL)
Terminal condition: Engine running - overrun condition
Voltage condition: none

Condition for fault memory entry
after a defined SA phase the lag period
K_LAVK_OBD_SA_T (2.5 sec) must be completed

Action in service
1. Check plug and wiring harness on pre-cat oxygen sensor
LSVK B1 (especially trim circuit wire IA),
2. If OK, replace oxygen sensor, replace DME as indicated

Fault effect and breakdown warning
MIL lamp on after engine runs 2x /Small influence on drivability

Driver information Warning light: MIL

Service instruction none

[C-los]

Hah, ya beat me to it.

Before hand, Do you have A/M X pipe from a reputable manufacturer? (i only ask this because sometimes ebay units may not install the O2 bung in the correct area, or correct depth causing a lag in response. But, considering you did not mention this happened after a modification, i will assume at this point that is not your issue.


So, > I < would suggest you double check your wiring one more time from the O2 plug to the DME. Make sure they're all good and and no excessive resistance, bad connections etc. If you have any type of aftermarket tune, i'd probably suggest you back it up, and update your DME to the latest OEM Tune/Software to rule out any bugs in the tuning. weird shit happens, i assure you.

Afterwards, You can either:
A) replace the Oxygen sensors with a new Set of OEM's one last time to verify it's not a weird fluke, install, etc.
if the issue returns, replace the DME.

B) go straight for a DME.

Wish i had better news

[dpaul]

Originally Posted by C-los

A) replace the Oxygen sensors with a new Set of OEM's one last time to verify it's not a weird fluke, install, etc.
if the issue returns, replace the DME.

B) go straight for a DME.

(

That's a very interesting hypothesis, that the DME is destroying O2 sensors. I've never encountered such a situation. Could you provide a link to an example if where this has been shown to be the case?

[C-los]

i never said the dme is 'destroying' the oxygen sensors.
I said if OP wanted to double check the oxygen sensors one last time.

But, if it's not wiring, or the sensor going bad (lets be honest, 1 or 2 maybe bad luck sensor, but not 3 unless you're buying some uber cheap ass vato zone ass sensors..)

It's going to be the DME having internal issues, whether its due to tuning or somewhere malfunction (which is why i said get it flashed and updated to latest OEM tune/software)
If all else fails, the DME is having an issue.

Two posts UP, Green-Eggs posted the DIag track for this specific DTC. The dtc itself is not regardig a sensor failure, but actually information feedback either FROM the sensor, or WHEN the DME is reading it. it's basically like the DME is receiving some type of internal lag (think gaming, networks) which is triggering the dtc.

**
Condition for fault memory entry
after a defined SA phase the lag period
K_LAVK_OBD_SA_T (2.5 sec) must be completed
**


**
Action in service
1. Check plug and wiring harness on pre-cat oxygen sensor
LSVK B1 (especially trim circuit wire IA),
2. If OK, replace oxygen sensor, <B>replace DME as indicated</B>
**

[dpaul]

Originally Posted by C-los

i never said the dme is 'destroying' the oxygen sensors.

**

With all due respect, you were suggesting that.

If you had read what the OP wrote, you would note that pre-cat sensors on one bank were being rendered unusable, i.e. destroyed. It happend twice in a period of a few weeks. After receiving the code, the OP stated that he swapped the 'bad' sensor to the other side, and the code followed to that side.

Thus, that sensor is dead, permanently. If it was a DME problem, the code would not have followed the bad sensor to the other side. This not consistent with a DME error and not consistent with a wiring or connector problem.

Also, regarding the possibility that the tune or the test pipes are contributing to this problem, the OP stated that the tune and test pipes were installed some number of years ago and this problem is recent. Unclear to me why it would take 3 years for a problem with the tune and test pipes to manifest.

I have no plausible explanation for what the OP reports. If you do, I'm sure we would all like to hear it.

[bmwlover0725]

Update: First off, thank you everyone for your help. I was panicking over this one just due to how worn this engine is at this point. It turned out to be spark plugs. I had NGK double platinums in it for the last 50k miles. They were just shot. Threw new ones in and monitors all set it one drive. The sensors are all fine. Anyone who wants a brand new discounted O2 sensor lemme know

[bmwlover0725]

Edit: 8 monitors did set and all was well, but now the CEL is on again...

[C-los]

D-paul, no where in my post did i sugget they were dead. i asked about his x pipe, and i said he could replace them (o2's) again if he wanted to, to double check.

I didn't say the tune was the cause, i stated he should revert back, to rule it out. software does strange things at times.

Also, he stated the issue is on BANK 1 ONLY, when he swapped the sensors, it fouled bank 1 again. it chases to bank 2 cause yes, the sensor is possibly dead, throwing a code.

Either way, doesn't matter anymore. He swapped some plugs and all monitors set, so unless he just changed the sensors AGAIN as i suggested, the sensors weren't "dead".

Either way, doesn't matter now.
To OP:

awesome, hope it stays fixed!