What exactly causes code 276A?

I just swapped a 2004 760Li engine into my 2003 760Li.

I thought I would be doing myself a favor by using the 2003 DMEs from my own car, on the 2004 motor, in my 2003 car. I figured I would avoid needing to re-program control modules to match each other.

I get consistent 276A on both DME1 and DME2, and rough running when it goes into closed loop.

do you know the nature of what causes 276A? (I basically get it-- looking for specific examples)

in DIS the info in the bottom pane is:

Control-Module selection
fault when determining hardware (Master / Slave)

I realize I will have to try some experiments. Like, swapping the two DMEs with each other (I could have mixed them up) and also, using the 2004 DMEs that came with the motor with my 2003 car.

OK I figured it out. Was in a hurry to get to work and could not stop and try some experiments. 276A means: your stuff is plugged in all wrong.

I had the two DMEs correct, since they have the large ZIF plugs, but the engine harness wires that I unplugged from the other units, was not correclty plugged back in right. basically a grey was in the black row and a black in the grey row. The wiring was bent in such a way that it looked like they should go there, but... this is BMW. Everything was color-coded. Black with black row and grey with grey row. Since there's almost no hits for error 276A on the entire web, hopefully my stupidity will help future generations.

When I pulled the old motor and it's harness, I asked asked a pal to do it while I worked on another area, and I forgot to ask him to document how it plugged in.

276A (P0420) Catalytic-converter conversion – Catalytic-converter efficiency too low.

The catalytic converter may be deteriorating, causing the catalytic converter monitoring to store the above fault in the DME memory.

I "did" see that one on the web. it appeared to be associated with a 2008 or later Mini, I think. BMW seems to be recycling that error code. 276A in DIS on a 2003 760Li is described in DIS as:


Control-Module selection
fault when determining hardware (Master / Slave)

what I was asking was: what real world cases cause it? and now I know because I had my stuff plugged in wrong.

Thank God you found out the error..

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