Seat Leon Diesel Gearbox Issues

Alright, so I'm having some serious issues with my 2003 Seat Leon diesel. Basically, the gearbox is acting up big time. Shifting with the paddle shifters is impossible, the gearbox slips and shifts really uncleanly, and there's this awful grinding noise when it actually does shift. The paddle shifters are also super slow to respond. The car keeps going into emergency mode, and I've got an error stored in the error memory. I'm thinking it's the transmission control unit, but I wanted to get some other opinions before I start throwing money at it. Anyone experienced similar transmission problems or car computer issues with their Leon?

4 comment(s)

Sounds like a dodgy transmission control unit to me. I had a similar issue with my Leon, although it's a newer model. Symptoms were almost identical: slipping gears, emergency mode, the works. Have you checked the error codes with an OBD2 scanner? That's the first thing I'd recommend. It could also be low transmission fluid, but given the grinding noises, I'm leaning towards the car computer being the culprit. Transmission problems are never fun!

Thanks for the quick reply! Yeah, I did check the error codes, and it points towards the transmission control unit being defective. You mentioned a similar issue, was it definitely the control module in your case? And did you manage to fix it yourself, or did you take it to a workshop?

Yep, for me, it was 100% the control module. Tried everything else first – fluid change, checked the wiring. Ended up being the car computer itself. I wouldn't recommend tackling a transmission repair like that yourself unless you're seriously confident. You'll need specialized tools and diagnostic equipment. Best bet is to take it to a trusted mechanic who knows their way around car computers.

Thanks a lot for your help! I took it to a local mechanic, and it was indeed the transmission control unit. They replaced it, and it cost me around 1000€. Ouch! But at least my Leon is running smoothly again.

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