Previa transmission control unit issue

That sounds remarkably similar to an issue I had with my old BMW 5 series. Although the brands are different, the symptoms you're describing align closely with what I experienced. In my case, the paddle shifters became unresponsive intermittently, and I also noticed the gearbox shifting erratically. It was like driving a car possessed by a shifting demon. Did you notice if this issue is more apparent under specific conditions, such as during colder weather or after prolonged use? Have you checked the transmission fluid level and condition? While a faulty control unit seems likely, it's worth eliminating simpler possibilities.

Interesting analogy with the 'shifting demon'! The issue does seem more pronounced when the engine's cold, like it's protesting the morning commute. Fluid level is fine, and the fluid itself looks okay, no burnt smell or metal shavings. What was the eventual diagnosis and fix for your BMW? Was it definitely the control unit, or did it turn out to be something else masquerading as the same problem?

Indeed, the shifting demon analogy does seem fitting in these situations. In my case, after thorough diagnostics, it was confirmed that the transmission control module was the root cause. The module had become corrupted, leading to erratic signals being sent to the transmission. Given that you've already checked the fluid level and condition, and the problem is exacerbated when the engine is cold, a faulty control unit seems increasingly probable. I would suggest consulting with a qualified technician to perform a detailed diagnostic scan and confirm the fault. It is probably time to take it to the workshop, as you cannot fix it yourself without specialist tools.

Thanks for the insight. It's helpful to know someone else battled a similar gremlin. Dropped it off at the shop, and they confirmed it's the transmission control unit. Quoted 1000€ for the replacement and reprogramming. Ouch, but at least I know what's up. Thanks again for the help!