Code UO302, Software Incompatibility with Transmission Control Module

ENIU93

MEMBER
2004 BMW 318I
2.0L
4 CYL
2WD
AUTOMATIC
78,900 MILES

Hi my car developed its problem after it was left un-used for four days in freezing weather -10. Before that it run faultless. The engine looks like its misfiring, there is a strong smell of petrol which makes me think its running rich. The OBDII keeps bringing out code: UO302 - Software Incompatibility with Transmission Control Module. I looks to me like an electrical issue with the bus communication system but I do not know where to start, please help me.

1 Reply

STEVE W.

MECHANIC
13,452 POSTS

Welcome to 2CarPros.
With a BMW, unless you are using a factory level scan tool don't trust the codes you get. The description would have me looking under the engine cover for any rodent damage or water entry into a connection for the coils. I would also check the coils themselves. At those temperatures even a small drop of moisture could freeze and damage the internal parts.
A misfire would give you the gas smell as it would be pushing un-burnt fuel out the exhaust, I would try to avoid running it as much as possible, only for testing. The easiest testing would be to disconnect one ignition coil at a time, the one you disconnect that doesn't shut the engine down is the one to start with. Be advised that the earlier BREMI coils break very easily. It is possible one has failed just from the cold.