Hey, sounds like a real pain. I had a similar issue with my 2018 Mazda CX5 a while back. It's not as miles long as yours, but trust me, it started showing similar symptoms; all that erratic shifting and noisy gear swapping. Turned out, you hit the nail on the head; it was a defective Transmission Control Unit (TCU). Dropped it off at my local garage, and they confirmed my doubts right off the bat. The TCU was shot and needed replacing. Replacing the TCU seems to have sorted the problem; the shifting returned to normal, and the unsettling noises disappeared. Not gonna sugarcoat it, it was indeed a serious problem. The TCU is responsible for managing the gears and transmission, so when it goes haywire, you could potentially end up with severe transmission damage if ignored. I know you've had a rough run with your mechanic, but a good, experienced one should be able to fix this up. So, take a deep breath, find a trustworthy mechanic, and get your TCU checked. It's not the end of the world, but it sure is something you shouldn't overlook. Good luck with it and keep us posted. Cheers!

Hey there, thanks for the heads-up, really appreciate it. Sounds like you nailed it with your CX5. Just one quick thing - do you remember how much you were out of pocket for the whole TCU replacement gig? And has there been any other transmission drama since the fix? My Mazda hasn't given me any major snags before, but this issue surely has me chewing my nails. I'm going to hunt around for a competent mechanic, can't handle another frustrating experience like the last one. Thanks again and I'll definitely keep you guys in the loop on how things go. Cheers!

Hey! I totally understand your worries. I remember all too well the stress when I had to shell out for that my TCU repair job. It wasn't exactly a bargain, will tell ya that - set me back a cool 1000€. But, you know what? After the fix, my Mazda’s been running smooth as silk. I’ve had zero gearbox issues and the beast’s been roaring ever since. So, while it may sting your wallet a little, trust me, fixing that pesky Transmission Control Unit is vital. Think of it as a small investment for your ride's longevity. Your CX8 will thank you for it! Seriously though, make sure you find a good mechanic. They're worth their weight in gold. Good luck and do keep us posted. Cheers!

Hey, thanks a ton for the quick reply and easing my anxious mind. 1000€, huh? A bit of a shocker, but really, if it's a long-term fix, I'm ready to bite the bullet. Your experience and your roaring Mazda give me a ray of hope. Couldn’t agree more with you on the importance of a good mechanic. They are indeed unsung heroes. This time I’ll do my homework well. Can't wait to have my CX8 running silky smooth again. Fingers crossed, and here's hoping the mechanic won't disappoint me this time, haha. Sure thing I'll update ya'll when I get it sorted or if any surprises come my way. Thanks again for the advice. Cheers!