C6 Gearbox Problems

Citroen C6 gurus, my 2008 C6 diesel with 214327 km is having gearbox issues. Paddle shifters are unresponsive, shifts are sloppy, and sometimes it feels like it's slipping. I occasionally hear grinding noises, and the paddle shifters' response is slow. The dashboard lit up, and the car went into emergency mode. The diagnostic tool says there's a defective transmission control unit. Does that sound right? Is the control unit the culprit?

4 comment(s)

Sounds familiar. I had similar symptoms on my old Volvo V70: shifting issues, emergency mode. There was also some weirdness with the electronic systems. Have you checked the wiring harness and connections to the control unit? It could be corrosion or a loose connection. What fault codes are you getting?

Thanks! I did a quick visual inspection of the wiring, but nothing obvious. I'll take a closer look, though. The fault codes specifically point to the TCU itself. Wouldn't a wiring issue throw a different code?

True, usually a wiring issue throws a different code. But on my Volvo, the ECU reported internal errors, and it seemed like it needed immediate replacement. Turns out, it was just a bad ground connection. Still, if it's pointing directly at the TCU, you might need a new one. Get a proper diagnostic at a shop before replacing parts.

Thanks! I'll get a more in-depth diagnosis at the shop, but I suspect you're right, it's going to be the TCU. They quoted around 1000€ for the repair, which seems right.

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