So a couple weeks back I was out for a nice Sunday drive in my 335i, I downshifted into 3rd, floored it, and heard an insanely loud backfire. Then that damned half-engine light comes on and the car barely makes it home.
After reading the codes with the Cobb Accessport I decided to probe the pins on the DME connector to try to figure out what was going on.
The Transistor for injector #5 was toast, and after I saw what a replacement DME would cost from the dealer I figured I better just fix it myself. I took the part number off the MOSFET, spent $2.00 for a new one from digi-key and after a little bit of work with the hot-air gun I was back in business.
I was getting the following codes:
30bb - DME digital motor electronics, internal failure
0305
0306
0304
0300
29d1 - Misfire Cyl 5
29d2 - Misfire Cyl 6
29d0 - Misfire Cyl 4
29d9 - something about misfiring with low fuel level
29cc - Misfire Multiple Cylinders
So heres a few pictures in case anyone is unfortunate enough to have a similar problem occur.
Transistor pins were shorted together
Transistors labeled:
I stopped taking pictures after this point. But basically you just remove the bad MOSFET and install a new one in its place.
Then after everything was closed back up, it started and ran great.