[Nicholas Bentley]

Hello everyone. I need some advice. Sorry for the long post, but I feel the background is important. FYI, I'm no stranger to working on cars, but this is the first time I worked on the BMW myself.

I have a 2011 BMW 335i E90 LCI N55 Sedan with MEVD17.2 DME. It has 47,000 miles. I've owned the car for 8 years. It runs perfectly, very strong, no hesitation, no problems over the years, seriously like new. However, the BMW dealership noticed that there were minor signs of oil leaking around the oil cooler housing and oil filter housing (common problem on N54 & N55). They recommended that I change those gaskets, as well as the intake manifold gaskets and the gasket where the DME connects to the intake manifold, for about $1,400 for $35 worth of gaskets, so I decided to do it myself along with some other maintenance procedures while I was at it.

I changed the aforementioned gaskets, the oil filter & o-rings, the engine air filter, the cabin air filter, and I changed the oil, the coolant, and the spark plugs (gaped properly) while I was at it. All parts are genuine BMW or OE parts. The car was down for 4 days while I took my time with this (mainly to teach my son how to do these things) and the negative battery was disconnected before any electrical work began. All BMW recommended torque specs were followed for reassembly, and I did the coolant bleed procedure.

After I put everything back together, it will not start. The engine cranks over hard, but it just cranks, cranks, cranks & cranks, no start. If I press the start button without my foot on the brake just to turn on the ignition, the engine cooling fan comes on high speed. A lot of people will immediately think bad water pump, bad starter, etc., but remember these things worked perfectly fine 4 days ago. They are not suddenly going to stop working because of the basic maintenance I did.

The battery is brand new (replaced by dealer in December) and the voltage tests good. I tried disconnecting the IBS as a test, but no difference. I tried disconnecting the MAF sensor as a test, but no difference. INPA throws all of these codes on the DME. If I clear them, they come back after I try to start again. 3427 (never gets cleared), 28B0, 28A4, 28A9, 3157, 2C6F, 281A, 2BD9, 2937, 29E0, 29D0, 378F, 3446. CAS also throws A0B4 (will not clear), but I think that is because of all of the DME codes preventing the car from starting. All of those codes seem to indicate that the DME is not receiving information from all of the engine sensors (oil pressure, MAF, throttle, charge pipe pressure, coolant, etc.), and BMW N55 Codes List found elsewhere points to wiring harness and/or DME.

I know that it's impossible for ALL of those sensors and pieces of equipment to go bad at once, but my car seems to think so. Did I kill my DME somehow? INPA reads from it. All of the dash and iDrive settings seem to be there. Everything seems to work except the car will not crank.

There are 6 connectors on the DME. 4 of them are unique and can't be hooked up wrong. The 2 connectors closest to the front of the car are the same though and could potentially be connected backwards, but mine look correct based on all of the photos I've seen online. I was wondering if I hooked them wrong. Maybe I didn't press them down tightly enough or bent a pin. I'm going to check that today to be safe.

Basically none of this should have happened from the simple maintenance I did. I treat everything like it's made of glass (not rough on anything), so no banging the DME, no yanking cables, etc.

Any thoughts on what to check before I have to break down and drag it to the stealership? I have access to INPA (or ISTA/D) if there's anything I should be checking.

I'm going to check the fuses today.

[TheMidnightNarwhal]

What are the DME gaskets you are talking about? You had to unplug DME for that?

[Nicholas Bentley]

The MEVD17.2 DME on the 2011 N55 connects to the intake manifold. In theory, that is supposed to cool the DME. There is a gasket between the DME and the intake manifold. I had to remove the intake manifold from the car to replace both the intake manifold gaskets and the DME gasket, and that required removing all of the connectors from the DME.

[TheMidnightNarwhal]

Originally Posted by Nicholas Bentley

The MEVD17.2 DME on the 2011 N55 connects to the intake manifold. In theory, that is supposed to cool the DME. There is a gasket between the DME and the intake manifold. I had to remove the intake manifold from the car to replace both the intake manifold gaskets and the DME gasket, and that required removing all of the connectors from the DME.

Oh wow ok, I google that and see what you mean, didn't knew it was like that on N55.

As for your issue, if you say you cleared codes and they always come back perhaps you may have ESD fried it. When you were handling the DME, did you make sure to only hold it by the heatsink/casing and not touch pins at all?

You said you have ISTA? I would maybe follow the diagnosis procedure in that for your codes.

[Nicholas Bentley]

Yeah, only handled the casing; I never touched the pins.

[TheMidnightNarwhal]

Originally Posted by Nicholas Bentley

Yeah, only handled the casing; I never touched the pins.

OK.

Then I would definitely go through the ISTA diagnosis procedure since you have it. I think that's what the dealer would do anyway. And end up replacing the DME if the "fixes" in that fails..

[GoRomeo]

Yeah you probably bent a pin or something. Double check all the connectors are back in place along with hoses etc...

[Nicholas Bentley]

I know everything is connected, but a bent pin does concern me. I'm going to head out and start checking shortly. I'm also going to check all of the fuses before I take it apart again just in case it's something simple like that.

[bluewater328]

Given that you were around the intake manifold (and forgive me as I'm coming from the N52 realm) but are you sure you didn't disturb the ground cable that goes across the bay (with the cowl holder) or that you didn't pull an injector connection?

[Nicholas Bentley]

I'm pretty sure, but I'll check that out as well.

[arkie6]

The one thing that could possibly be common to all of these codes is a poor or absent ground connection. Also, when I first installed my JB4 in my '08 N54 335i, the fan kicked on full speed the first time I tried to start it after having the battery disconnected during the JB4 install. Reading over at N54tech, this was due to the JB4 sharing a ground point with the DME and it was sensing high engine temperature as a result. The fix for the JB4 is to split the grounds apart and install a new ground to the JB4. But the point of this discussion is that a poor ground connection to the DME can cause the fan to kick on high and possibly many of the other codes listed.

[Nicholas Bentley]

I took enough stuff off to get to the DME to check the cables. I pulled them and reconnected them to make sure they were tight. Put it all back together and cleared the codes. This time there were no stuck codes and nothing came back. Cranked right up.

I guess one or more of the cables didn't have a good connection before. What a relief that it wasn't a dead DME. Thanks everyone for the advice and help!!

[Nicholas Bentley]

Arkie6, good to know that about the JB4. I'm thinking about doing that soon.

[TheMidnightNarwhal]

Originally Posted by Nicholas Bentley

I took enough stuff off to get to the DME to check the cables. I pulled them and reconnected them to make sure they were tight. Put it all back together and cleared the codes. This time there were no stuck codes and nothing came back. Cranked right up.

I guess one or more of the cables didn't have a good connection before. What a relief that it wasn't a dead DME. Thanks everyone for the advice and help!!

Nice. Thank god didn't have to get a new DME at like 1500$

[bluewater328]

Glad you got it back up!👍

[GoRomeo]

Originally Posted by Nicholas Bentley

I took enough stuff off to get to the DME to check the cables. I pulled them and reconnected them to make sure they were tight. Put it all back together and cleared the codes. This time there were no stuck codes and nothing came back. Cranked right up.

I guess one or more of the cables didn't have a good connection before. What a relief that it wasn't a dead DME. Thanks everyone for the advice and help!!

Welcome! Glad you got it working again!