Astra Transmission Issues: Slipping & Warning Lights, Help!

Hey there! I can relate, I had a similar issue with my 2014 Vauxhall Insignia last year. I'd say I have some experience with cars, enough to do basic maintenance but not major repairs. My symptoms were pretty much identical to what you're describing. After taking it to my trusted workshop, it turned out to be a faulty transmission control unit. Had to shell out about 1000€ to get it sorted, but it's been running smoothly since then. Could you share some more details about your Astra? Like the mileage, engine size, and whether you've noticed any specific patterns when the issues occur (like when the car's cold or during specific gear changes)? This would help determine if you're dealing with the same problem I had. Also, have you had any recent transmission service done? Just to rule out simpler issues.

Thanks for sharing your experience! My Astra just hit 90105 KM and had its last service about 4 months ago. The issue tends to happen more when the car's warmed up, especially during highway driving. It's most noticeable when shifting between 3rd and 4th gear. Really hoping it's not as expensive as your repair was! Was your TCU replacement done at a Vauxhall dealer or an independent shop?

Hey again! Yeah, I remember my Insignia's issues very well, gave me quite a headache! To answer your question about the TCU replacement, I actually went with an independent specialist in the end. Found a really good shop that specializes in Vauxhall transmissions, and they charged me less than what the dealer quoted (they wanted nearly 1400€!). Your symptoms sound really similar to what I experienced, especially that 3rd to 4th gear issue. My car had about 85,000 KM when it started acting up. The fact that yours happens more when warmed up and during highway driving, that's exactly what I dealt with too. One thing I didn't mention in my first reply, before I got the TCU replaced, I tried changing the transmission fluid first (cost me about 150€), hoping it would solve the problem. Didn't work in my case, but might be worth checking in your situation since you're at 90K KM. Tell you what, if you're near [trying to keep costs down], I can recommend that specialist shop I used. They really knew their stuff with Vauxhalls, and they even offer a 2-year warranty on their TCU repairs. Let me know if you want their details!

Thanks so much for all this detailed info! Really appreciate you sharing your experience and the tip about the independent specialist. I think I'll start with getting the transmission fluid checked first, at least it's a cheaper option to rule out before diving into the TCU replacement. My wallet's definitely hoping it's just the fluid! The shop you mentioned sounds great, especially with that warranty. I'm actually in Manchester, so if your specialist is anywhere nearby, I'd love to get their details. Definitely prefer going to someone who knows their way around Vauxhalls specifically rather than taking a gamble with a unusual garage. Thanks again for all your help! I'll keep you posted on what I find out.