joseph_taylor10
Mini Roadster Transmission Control Unit Failure
Summary of the thread
A 2015 Mini Roadster diesel is experiencing transmission issues, including unresponsive paddle shifters, erratic shifting, grinding noises, and emergency mode activation, with diagnostics indicating a defective transmission control unit (TCU). A similar issue in another Mini was caused by a faulty speed sensor, but in this case, the problem was confirmed to be the TCU. Replacing and coding the TCU resolved the issues, restoring proper vehicle function.
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4 comment(s)
joseph_taylor10 (community.author)
Good point about the speed sensor. I've got the diagnostic report here, and it's only showing errors related to the transmission control unit itself. Do you remember if your symptoms were exactly the same? Paddle shifters not working, slipping gears, and going into limp mode?
lindaschwarz73
Yeah, my symptoms were very similar. The paddle shifters were the first to go, then the slipping started. I'd recommend getting a second opinion from a reputable workshop. They can run more in-depth diagnostics and confirm if it's definitely the TCU. Better safe than sorry, especially with gearbox issues.
joseph_taylor10 (community.author)
I had the Mini checked out, and it was indeed the TCU. Replaced it, coded it, and now it shifts like new. Cost me about 1000€, but worth it to get back on the road.
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MINI
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ROADSTER
lindaschwarz73
Interesting issue. I had similar gearbox issues with my Mini Cooper – not a Roadster, but the same engine and transmission, I think. It turned out to be a faulty speed sensor causing the ECU to freak out. Have you checked the sensor readings with an OBD scanner?