DME Codes 2A2C/2A2C

RayLivingston · 08-13-2018, 01:55 PM

After doing a bunch of work on my '07 335i, (new valve cover, new serpentine belt and idlers, new oil filter block gasket, etc.), I got it all back together, and running, BUT.... After a few minutes, the idle starts hunting, and I'm getting DME code 2A2B and 2A2C. Shortly after the first start, I blipped the throttle, and it threw a single fault - forget the number - but had to do with correlation between the manifold vacuum and throttle position. That one has not come back, so I'm inclined to ignore it.

As I understand it, the 2A2B/2A2C faults are related to the two primary O2 sensors. There was NO problem before I did all the work, and I did mess with the O2 sensor wiring, and a million other things, in the process of swapping the valve cover. I have to believe all the parts are just fine, and I somehow managed to mis-connect something when I put it all back together.

Any ideas what I could've done wrong? Seems to me the O2 sensor wiring cannot be re-connected wrong, as the cables are different lengths, and I don't think they would fit if not connected correctly. Perhaps something to do with the two vacuum solenoids, vacuum reservoirs, and plumbing at the right-front corner of the engine, next to the coolant reservoir? What are those for? I assumed they had something to do with the turbo waste gates, but perhaps they are emissions doo-hickeys?

Any suggestions welcome.

Regards,
Ray L.

RayLivingston · 08-13-2018, 02:24 PM

The "Throttle position/manifold vacuum correlation" fault did come back. It is code 2D2E. I did go for a short drive, and it seemed ok-ish, but was slow returning to idle. If I "blip" the throttle in neutral, the idle gets really random and rough - ranging anywhere from 600-1200 RPM. Switch the engine off and back on, and it seems ok, at least for a while.

So, what did I do wrong?? It's gotta be something really simple and really stupid...

I saw mention of a vacuum line going to the throttle body in a thread about the 2D2E code. I did briefly unbolt and lift the intake manifold, to get to the top-rear bolt holding the oil filter block on. I may have disconnected that line and forgotten to re-connect it. Where does it come from, and where does it connect to the TB?

Regards,
Ray L.

gbalthrop · 08-13-2018, 02:52 PM

Quote:

Originally Posted by RayLivingston

...As I understand it, the 2A2B/2A2C faults are related to the two primary O2 sensors. There was NO problem before I did all the work, and I did mess with the O2 sensor wiring, and a million other things, in the process of swapping the valve cover.

Hi Ray,

That plastic fitting on the Bypass Hose at the OFH has caused trouble for a LOT of people -- glad to hear you were able to hit that "curve ball."

It DOES sound like you have Bank 1 & Bank 2 Pre-cat sensor connectors swapped. Reasons for that observation: runs OK until engine has operated long enough to go to closed-loop operation where pre-cat sensor signals begin to regulate fueling enrichment. It would be helpful to know if both banks too rich, both too lean, or one of each.

What code reader(s) do you have? Can you get a P-code, or a Definition of the BMW FCs you list?

Reason for asking is that the BMW FCs you list each have TWO possible definitions, either Rich or Lean, and the P-code would be definitive. According to Bentely, BMW FC "2A2B" can be either P0171, too Lean, Bank 1, or P0172, too RICH, Bank 1. BMW FC 2A2C likewise can mean either too rich or too lean for BANK 2.

Checking with a P-code reader should nail it.

I'm NOT familiar with the connector locations on the N54 engine, and can't say if it is possible to swap connectors.. If you did NOT actually remove the sensors from the manifolds (possibility of physical install location swap) but DID disconnect the Lambda sensor electrical connectors, then confirm correct by wire colors if you can. Note in the circuit diagram the ONLY one of the 6 wires that has a DIFFERENT color is pin #2.

TIS circuit diagram for 2007 335i E90:
https://www.newtis.info/tisv2/a/en/e...ontrol/x5UZsdI

Installation Location:
https://www.newtis.info/tisv2/a/en/e90-335i-lim/SCO2U5k

Connector View:
https://www.newtis.info/tisv2/a/en/e...i-lim/CT8vHPzV

George

RayLivingston · 08-13-2018, 02:53 PM

And..... Now codes 29E0 and 29E1...

gbalthrop · 08-13-2018, 03:10 PM

Quote:

Originally Posted by RayLivingston

The "Throttle position/manifold vacuum correlation" fault did come back. It is code 2D2E.

Can't answer any of your questions about vacuum lines on N54, but here is Bentley definition of that fault code:
P112F | 2D2E | Manifold Absolute Pressure to Throttle Angle - Too High

You can probably find vacuum line and Throttle Valve information in TIS or Bentley. If you don't have Bentley, you can download it here:
http://www.georgebelton.com/335i.tech/bentley.php

Any chance you didn't connect Throttle Valve connector?
https://www.newtis.info/tisv2/a/en/e...ration/ObrNux6

Happy hunting,
George

RayLivingston · 08-13-2018, 03:13 PM

The weirdness just keeps on coming.... When I decided to pull the car back in the garage, it has virtually NO brakes! I started the engine with my foot on the brake, then shifted into drive, and the car started moving! I had to press REALLY hard on the pedal to stop it! WTF???

And, joy of joys, the new valve cover is leaking. SO, that's gotta come off again to see WTF is going on.

There's a rising probability this car will get stolen, parked somewhere, and set on fire real soon at this rate. Most !@#$%^&*( frustrating car I've ever owned...

My code reader is a Foxwell NT510 with the BMW add-on software. Not sure if it gives P-codes, but I'll check when I get back from running some errands.

I did not remove the O2 sensors, just un-did the harness connectors on top of the intake manifold, to get the harnesses out of the way when the valve cover came off. Also un-did the harnesses to the two solenoids on the exhaust side of the engine, but those definitely cannot be connected wrong, since one is VERY short, and the other quite long. I will remove the head cover (again!) and double-check the O2 sensor harnesses.

I checked the TPS harness, and it is connected.

The vacuum line to the throttle body was never disconnected.

I did find the small vacuum lines to one of the two actuators (or whatever they are) on the inlet duct was in bad shape, so repaired that. But it did not change anything.

Regards,
Ray L.

gbalthrop · 08-13-2018, 04:18 PM

Quote:

Originally Posted by RayLivingston

...When I decided to pull the car back in the garage, it has virtually NO brakes!...I had to press REALLY hard on the pedal to stop it!

As you hopefully know, the vacuum brake booster is supplied vacuum via a separate vacuum pump driven by the engine off a chain drive. The pump is located on the left-front (US Driver side) of the engine, immediately forward of the HPFP.

Check for a loose or damaged vacuum hose between the vacuum pump and the booster.

George

RayLivingston · 08-13-2018, 07:46 PM

Quote:

Originally Posted by gbalthrop

As you hopefully know, the vacuum brake booster is supplied vacuum via a separate vacuum pump driven by the engine off a chain drive. The pump is located on the left-front (US Driver side) of the engine, immediately forward of the HPFP.

Check for a loose or damaged vacuum hose between the vacuum pump and the booster.

George

I did NOT know that, but I was wondering because I can't see any way for a standard MAP-driven booster to do that! I'll check that out tomorrow, since I have to take off the !@#$%^& valve cover again - it leaks!

Why on earth would they NOT use manifold vacuum for the brake booster?

Regards,
Ray L.

RayLivingston · 08-13-2018, 08:35 PM

I am SUCH an idiot! The brakes are fine. I have the airbox off, and since it was off, I did not have the vacuum line to the brake booster connected. Hence, NO boost. I had no idea that was what that pipe was for! Now I know!

I've started removing the valve cover, again. The first time, I left the harnesses running over the engine connected to the buig junction box in the right-rear corner of the engine bay. This time I decided to disconnect them, to make it easier to get the valve cover in and out. BUT, it appears to be impossible to do so! The three harnesses are all inter-connected, and also connected to another harness that exits the box on the other side. There is no way to separate the three harnesses from each other, or from that one exiting the other side. So, disconnecting all that stuff only bought me a few inches of slack! Is there no way to completely disconnect the harnesses and get them completely off the engine? I REALLY want to be able to get the piece that holds all the ignition coil and injector wiring completely out of my way when working on the valve cover.

Regards,
Ray L.

RayLivingston · 08-13-2018, 08:50 PM

I still don't see how the O2 sensor cables could be swapped. And, whoever worked on it last, put orange paint dots on the front pair, making it even harder.

The two harnesses are different - one is in a light gray loom, the other in a black loom. One connector is near the front of the engine (the black loom one), the other near the back of the engine (the gray loom one). This seems to agree with the wiring I see in several photos I found courtesy of Google.

I assume.... the front one is for the sensor on the front 3 cylinders, and the back one is for the sensor on the rear 3 cylinders?

Regards,
Ray L.

RayLivingston · 08-13-2018, 09:33 PM

Quote:

Originally Posted by gbalthrop

If you did NOT actually remove the sensors from the manifolds (possibility of physical install location swap) but DID disconnect the Lambda sensor electrical connectors, then confirm correct by wire colors if you can. Note in the circuit diagram the ONLY one of the 6 wires that has a DIFFERENT color is pin #2.

Oddly, the two harneses are color-coded identically, both on the sensor-side and the ECU side. The only visible difference is the loom colors on the sensors.
Both looms are black on the ECU side harnesses. So no clues there.

Regards,
Ray L.

gbalthrop · 08-13-2018, 09:38 PM

Quote:

Originally Posted by RayLivingston

...Is there no way to completely disconnect the harnesses and get them completely off the engine? I REALLY want to be able to get the piece that holds all the ignition coil and injector wiring completely out of my way when working on the valve cover.

Hi Ray,

Two links from TIS:

Valve Cover (aka Cylinder Head Cover) Removal:
https://www.newtis.info/tisv2/a/en/e...th-lid/4Tmm7qa

See the "Necessary Preliminary Tasks" which include the following:

Wiring Harness Removal:
https://www.newtis.info/tisv2/a/en/e...h-lid/8IXo7mEo

Good luck,
George

RayLivingston · 08-13-2018, 09:51 PM

Quote:

Originally Posted by gbalthrop

Hi Ray,

Two links from TIS:

Valve Cover (aka Cylinder Head Cover) Removal:
https://www.newtis.info/tisv2/a/en/e...th-lid/4Tmm7qa

See the "Necessary Preliminary Tasks" which include the following:

Wiring Harness Removal:
https://www.newtis.info/tisv2/a/en/e...h-lid/8IXo7mEo

Good luck,
George

Interesting! I looked at thos big connectors and wondered if they could be take apart, but saw no obvious sign that they could. Will look at that in the AM.

Thanks again!

Regards,
Ray L

gbalthrop · 08-13-2018, 11:19 PM

Quote:

Originally Posted by RayLivingston

Interesting! I looked at thos big connectors and wondered if they could be take apart, but saw no obvious sign that they could.

A "Minor" in 'Sadism' must be required for those who "Major" in 'EE' and later design automotive electrical connectors. It seems every model tries to come up with something more difficult to release than the earlier model.

They are called "Connectors" because they are supposed to "disconnect."

Perhaps with a good night's sleep...

The range of possibilities:

RayLivingston · 08-14-2018, 02:12 PM

AAAAARRRRRGGGGGGGHHHHHHH!!!! Here's today's news:

1) Removed the valve cover to investigate the oil leak. Found the gasket intact, all surfaces pristine, no obstacles. That left one possibility - something wrong with the new valve cover. That was, indeed the case. Long story short - dimensional problems that caused it to all go together with, best as I can tell, ZERO compression of the gasket! Fortunately, most of the problem was in the new bolts - the spacers were too long, by about 1mm! Using the old, factory bolts, got me back into an acceptable range of compression - actually just a bit more than the factory cover provided. I did have to slightly shorten two of the front ones, due to a minor difference in the size of the two front corner holes in the cover.

2) I believe I found the cause of all the DME faults. I re-connected the harnesses following logic - based on cable lengths, the orange paint dots on one pair of connectors, and numerous on-line photos which showing the gray harness being for the front O2 sensor, and connecting to the rear harness on the intake manifold. Well, whatever numb-nuts installed these sensors put the one with the gray harness on the REAR cat! Next time I'll take photos before taking it apart, and NOT assume it is assembled correctly.

Regards,
Ray L.

gbalthrop · 08-16-2018, 11:09 AM

Quote:

Originally Posted by RayLivingston

...whatever numb-nuts installed these sensors put the one with the gray harness on the REAR cat! Next time I'll take photos before taking it apart, and NOT assume it is assembled correctly.

So the 2A2B/2A2C Fault Codes were the result of the pre-cat sensor connectors being swapped? And the cause of your re-connecting them as swapped was that prior installation had put Bank 1 (longer harness) sensor in Bank 2, and vice-versa?

Glad you got it sorted,
George

RayLivingston · 08-16-2018, 01:59 PM

Quote:

Originally Posted by gbalthrop

So the 2A2B/2A2C Fault Codes were the result of the pre-cat sensor connectors being swapped? And the cause of your re-connecting them as swapped was that prior installation had put Bank 1 (longer harness) sensor in Bank 2, and vice-versa?

Glad you got it sorted,
George

Well, I'm honestly quite confused at this point. The sensor with the gray line IS on the rear cat. So, it made sense to me to re-route the harnesses so that could connect to what WAS the front connector. But, when I started the engine, I actually got a fault that said, explicitly, the two sensors were swapped. So, I really do not know what was going on. But it is now all back together, running fine, and NO faults whatsoever.

Sometimes, these things are just bizarre...

Regards,
Ray L.

stephenf121 · 08-31-2018, 08:44 PM

OP i just recently did all the same work as yourself (valve cover gasket, oil filter housing gasket, etc etc) started my car and i am getting the exact same symptoms as you... stumbling idle, misfire and fuel mixture codes, o2 sensor codes etc... have no idea what to do. Any advice? I really don't want to pull the valve cover off again...

08-13-2018, 01:55 PM	#1
RayLivingston Lieutenant 140 Rep 445 Posts Drives: '07 335i Sedan Join Date: Aug 2018 Location: California iTrader: (0)	DME Codes 2A2C/2A2C After doing a bunch of work on my '07 335i, (new valve cover, new serpentine belt and idlers, new oil filter block gasket, etc.), I got it all back together, and running, BUT.... After a few minutes, the idle starts hunting, and I'm getting DME code 2A2B and 2A2C. Shortly after the first start, I blipped the throttle, and it threw a single fault - forget the number - but had to do with correlation between the manifold vacuum and throttle position. That one has not come back, so I'm inclined to ignore it. As I understand it, the 2A2B/2A2C faults are related to the two primary O2 sensors. There was NO problem before I did all the work, and I did mess with the O2 sensor wiring, and a million other things, in the process of swapping the valve cover. I have to believe all the parts are just fine, and I somehow managed to mis-connect something when I put it all back together. Any ideas what I could've done wrong? Seems to me the O2 sensor wiring cannot be re-connected wrong, as the cables are different lengths, and I don't think they would fit if not connected correctly. Perhaps something to do with the two vacuum solenoids, vacuum reservoirs, and plumbing at the right-front corner of the engine, next to the coolant reservoir? What are those for? I assumed they had something to do with the turbo waste gates, but perhaps they are emissions doo-hickeys? Any suggestions welcome. Regards, Ray L.
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08-13-2018, 02:53 PM	#4
RayLivingston Lieutenant 140 Rep 445 Posts Drives: '07 335i Sedan Join Date: Aug 2018 Location: California iTrader: (0)	And..... Now codes 29E0 and 29E1...
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08-13-2018, 03:13 PM	#6
RayLivingston Lieutenant 140 Rep 445 Posts Drives: '07 335i Sedan Join Date: Aug 2018 Location: California iTrader: (0)	The weirdness just keeps on coming.... When I decided to pull the car back in the garage, it has virtually NO brakes! I started the engine with my foot on the brake, then shifted into drive, and the car started moving! I had to press REALLY hard on the pedal to stop it! WTF??? And, joy of joys, the new valve cover is leaking. SO, that's gotta come off again to see WTF is going on. There's a rising probability this car will get stolen, parked somewhere, and set on fire real soon at this rate. Most !@#$%^&*( frustrating car I've ever owned... My code reader is a Foxwell NT510 with the BMW add-on software. Not sure if it gives P-codes, but I'll check when I get back from running some errands. I did not remove the O2 sensors, just un-did the harness connectors on top of the intake manifold, to get the harnesses out of the way when the valve cover came off. Also un-did the harnesses to the two solenoids on the exhaust side of the engine, but those definitely cannot be connected wrong, since one is VERY short, and the other quite long. I will remove the head cover (again!) and double-check the O2 sensor harnesses. I checked the TPS harness, and it is connected. The vacuum line to the throttle body was never disconnected. I did find the small vacuum lines to one of the two actuators (or whatever they are) on the inlet duct was in bad shape, so repaired that. But it did not change anything. Regards, Ray L.
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08-13-2018, 08:35 PM	#9
RayLivingston Lieutenant 140 Rep 445 Posts Drives: '07 335i Sedan Join Date: Aug 2018 Location: California iTrader: (0)	I am SUCH an idiot! The brakes are fine. I have the airbox off, and since it was off, I did not have the vacuum line to the brake booster connected. Hence, NO boost. I had no idea that was what that pipe was for! Now I know! I've started removing the valve cover, again. The first time, I left the harnesses running over the engine connected to the buig junction box in the right-rear corner of the engine bay. This time I decided to disconnect them, to make it easier to get the valve cover in and out. BUT, it appears to be impossible to do so! The three harnesses are all inter-connected, and also connected to another harness that exits the box on the other side. There is no way to separate the three harnesses from each other, or from that one exiting the other side. So, disconnecting all that stuff only bought me a few inches of slack! Is there no way to completely disconnect the harnesses and get them completely off the engine? I REALLY want to be able to get the piece that holds all the ignition coil and injector wiring completely out of my way when working on the valve cover. Regards, Ray L.
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08-13-2018, 08:50 PM	#10
RayLivingston Lieutenant 140 Rep 445 Posts Drives: '07 335i Sedan Join Date: Aug 2018 Location: California iTrader: (0)	I still don't see how the O2 sensor cables could be swapped. And, whoever worked on it last, put orange paint dots on the front pair, making it even harder. The two harnesses are different - one is in a light gray loom, the other in a black loom. One connector is near the front of the engine (the black loom one), the other near the back of the engine (the gray loom one). This seems to agree with the wiring I see in several photos I found courtesy of Google. I assume.... the front one is for the sensor on the front 3 cylinders, and the back one is for the sensor on the rear 3 cylinders? Regards, Ray L.
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08-13-2018, 02:24 PM	#2
RayLivingston Lieutenant 140 Rep 445 Posts Drives: '07 335i Sedan Join Date: Aug 2018 Location: California iTrader: (0)	The "Throttle position/manifold vacuum correlation" fault did come back. It is code 2D2E. I did go for a short drive, and it seemed ok-ish, but was slow returning to idle. If I "blip" the throttle in neutral, the idle gets really random and rough - ranging anywhere from 600-1200 RPM. Switch the engine off and back on, and it seems ok, at least for a while. So, what did I do wrong?? It's gotta be something really simple and really stupid... I saw mention of a vacuum line going to the throttle body in a thread about the 2D2E code. I did briefly unbolt and lift the intake manifold, to get to the top-rear bolt holding the oil filter block on. I may have disconnected that line and forgotten to re-connect it. Where does it come from, and where does it connect to the TB? Regards, Ray L.
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08-14-2018, 02:12 PM	#15
RayLivingston Lieutenant 140 Rep 445 Posts Drives: '07 335i Sedan Join Date: Aug 2018 Location: California iTrader: (0)	AAAAARRRRRGGGGGGGHHHHHHH!!!! Here's today's news: 1) Removed the valve cover to investigate the oil leak. Found the gasket intact, all surfaces pristine, no obstacles. That left one possibility - something wrong with the new valve cover. That was, indeed the case. Long story short - dimensional problems that caused it to all go together with, best as I can tell, ZERO compression of the gasket! Fortunately, most of the problem was in the new bolts - the spacers were too long, by about 1mm! Using the old, factory bolts, got me back into an acceptable range of compression - actually just a bit more than the factory cover provided. I did have to slightly shorten two of the front ones, due to a minor difference in the size of the two front corner holes in the cover. 2) I believe I found the cause of all the DME faults. I re-connected the harnesses following logic - based on cable lengths, the orange paint dots on one pair of connectors, and numerous on-line photos which showing the gray harness being for the front O2 sensor, and connecting to the rear harness on the intake manifold. Well, whatever numb-nuts installed these sensors put the one with the gray harness on the REAR cat! Next time I'll take photos before taking it apart, and NOT assume it is assembled correctly. Regards, Ray L.
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08-31-2018, 08:44 PM	#18
stephenf121 Second Lieutenant 43 Rep 206 Posts Drives: 2007 335i Join Date: Oct 2015 Location: Ohio iTrader: (0)	OP i just recently did all the same work as yourself (valve cover gasket, oil filter housing gasket, etc etc) started my car and i am getting the exact same symptoms as you... stumbling idle, misfire and fuel mixture codes, o2 sensor codes etc... have no idea what to do. Any advice? I really don't want to pull the valve cover off again...
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