Just a quick post for Internet longevity. (There wasn’t a dedicated Honda community I could find on Lemmy and fuck Reddit, so here I am.)
From what I could find online, some Honda and Acura owners will get stuck with a TT06 (or TT04) error when the system attempts to update itself. I bought my '23 Accord new and have been plagued with this for the last two years. This may affect other '23 models, but I cannot confirm this by just reading through rando Honda forums.
The first service bulletin with a fix, that doesn’t work, is here for Accords: https://static.nhtsa.gov/odi/tsbs/2023/MC-10237040-0001.pdf The error will return after another update is available as it did for me. (Simply doing a TCU reset doesn’t fix the issue.)
The Honda service tech will need to contact Honda and force an update override to get the latest TCU updates installed. (While I am not a Honda tech, I am a nerd. There was an off-by-one issue with time synchronization which I know can cause all kinds of issues with various flavors of hardware and software update systems.)
I had to call Honda and open a case with them directly, have them contact the service manager directly so they could get updated service instructions. (Weird.)
TCU updates that were installed for my Accord that seems to have fixed the issue: 
Cheers! I was just doing a brain-dump while this was still fresh in my mind and the firmware screenshots were still at the top of my photo list.
My apologies for a somewhat irrelevant post in this community, but cars.
It’s only weird until you realize (a) car companies are working hard to software-limit owners’ and independent shops’ ability to perform maintenance, and (b) car companies are not exactly known for high-quality computer code.
Stuff like this and every time I have to deal with similar type of fuckery, I stop and really consider buying a Lincoln Town Car and just try to keep it running as long as I can lol.
All I’ll say is, I’m happy my 1994 Honda still basically works well.
And you can keep it running indefinitely.
We have several of that vintage in the family for just that reason.
I miss my old Hondas. All of 'em. I had a '94 Accord, a '99 Accord, a '03 Civic, a '03 CRV, a '13 Accord Touring and now a '23 Accord Touring. I had a 2003 Mercedes C230 that was a very quick fling, but we don’t talk about that. (I have already started talking to a few dealers for dibs on a '26 Accord Touring.)
The 1994-2003’ish generation Accords were super easy to work on, less a few quirky things. I still keep a Honda crank shaft bolt tool in my toolbox for nostalgia reasons, actually. My 99 4-cyl Accord was the car I used to learn how to rebuild engines and it was super forgiving with any mistakes. (It was running with half a valve somehow, but that was pre-existing and something I discovered prior to me breaking other things.)