2012 35i fuel injector short circuit B+ codes

[Siggy]

I'm getting 2 codes, 2A00 and 2A14, injector cylinder 1 and cylinder 6 high voltage short circuit to B+ errors. I understand those two are triggered by the same thing in the ECU, if what I read is correct, so it really could be either, or both.

I found a technical bulletin from BMW that someone posted online that showed those codes and said it could be the power distribution box, the ECU, or the wires going to the injectors. I removed the power distribution box, cut it open and tested all fuses and they were all in tack so I assume that is working. I pulled the manifold and ECU out and shipped it off to be checked/repaired. They notified me they checked it and it functioned properly, no errors at all. The Technical Bulletin was very specific an in bold letters said "DO NOT REPLACE THE INJECTORS, IT IS NOT THEM" (paraphrasing).

I haven't checked all the individual wires going to the injectors yet, it's on my list of things to do, but that's next. I was hoping to find a schematic of the injectors so I could check the continuity of each injector wire going back to the plug but I haven't been able to locate that yet. So far, I haven't traced the injector wires to the plug yet so I'm not sure which plug I'm looking for to do that just yet. The ECU is still out of the car, I thought it might be easier to wring the wires out before I put the manifold back on.

Just checking in here to make sure I'm heading down the right path or if I'm completely in the wrong place. There appears to be very little about those codes online.

Any tips, suggestions, things to check?

[80stech]

I guess it depends on what the DME is looking at to set those codes but short to B+ would be most likely the injector shorted. Maybe you could swap injectors around just to rule that out for sure. For sure get a hold of a wiring diagram. What do you mean triggered by the same thing in the ECU? are they paired up in the same injector driver chip?
What are the symptoms??
What is the history? has someone maybe been doing some testing and jumpering ?

[Siggy]

Originally Posted by 80stech

I guess it depends on what the DME is looking at to set those codes but short to B+ would be most likely the injector shorted. Maybe you could swap injectors around just to rule that out for sure. For sure get a hold of a wiring diagram. What do you mean triggered by the same thing in the ECU? are they paired up in the same injector driver chip?
What are the symptoms??
What is the history? has someone maybe been doing some testing and jumpering ?

I've read that the same trigger in the ECU controls #1 and #6 so you shouldn't take that error to literally because it could be either one, not necessarily both.

The symptoms are the car shuts down those two cylinders and goes into the protection mode.

No history, been a great car, 205,000 miles on it, no one's messed with it. It was running fine, then did this coming out of a parking lot one day. I turned it off and on again and it ran fine for a few days. Did it again, restarted didn't help, I reset the codes with a reader, it ran for a couple weeks, then it came back and nothing I can do will make it stop.

No testing or jumpers on it. In searching for that code, I found a BMW technical service bulletin that specifically said it wasn't the injectors so I assumed, after some checking, that it was the DME, so I sent that out to be tested and repaired. They found no errors so I'm back to troubleshooting mode. Just hate to put the ECU and intake back on to test some things and thought I'd wring the wiring out to make sure I didn't have a broken wire somewhere I can't see but I can't locate the wiring diagram online, other than stuff that's so blurry you can't read any text.

[80stech]

What are you using to read the codes and get the descriptions? Maybe the code description isn't translated properly and giving some wrong direction as to what is going on?? Maybe approach it as having a miss and forget about the codes and see what that brings. 1 and 6 are probably the most likely to have ring/compression issues and the DME will shut off injectors if cylinders aren't producing enough power. There is a live power balance available if you have a diagnostic tool that can access it. Just throwing some stuff out there!

[Siggy]

Just using a Foxwell scanner for the codes.

I do have an oscilloscope so that was next, but while the manifold is off, I thought I'd have a clear shot to using a multimeter to check each injector wire and make sure there wasn't anything obvious like a broken wire.

I traced the wires to this plug that goes into the ECU...



Then started probing every injector, each injector having 2 wires so I could map it all out on paper.

Got to the last injector, cylinder 6, and went to probe it and noticed that one of the pins in the plug was melted.



Got my scope camera out and looked into the injector part of the plug and I can see a slight bit of goo on that one pin area at the bottom.

Looks like water got into the area and filled up that entire area at some point prior to me owning it.

It's dry as it can be but clearly, at some point, that well around #5 and #6 was full of water.

Think that could be the issue?

[80stech]

There you go! If that's the case then the injector winding might actually be shorted. See how the winding ohms out compared to the others and check if there is any continuity to ground.

[Siggy]

Originally Posted by 80stech

There you go! If that's the case then the injector winding might actually be shorted. See how the winding ohms out compared to the others and check if there is any continuity to ground.

Will do, thanks for the help! Much appreciated. Will report back.

[Siggy]

Looks like a bad injector. Five injectors measure 18 and the #6 injector is measuring 7, so less than 1/2 of what all the others. My guess is it shorted out and smoked the plug a little.

New injector ordered so we'll see how that all goes.

[80stech]

Good work! It would be a really good idea to replace the connector (or at least the contacts) as well, excessive heat can make the metal more susceptible to oxidizing and causing problems down the road.

Back in the day there would have been a good chance that the injector driver in the DME was damaged as well but modern chips have a lot more safety features built in so hopefully that's all OK