TechSavvy2

Yes - they ran real-time diagnostics on it and reproduced it a handful of times. The rear bumper sensors were “detecting” objects behind the vehicle. Turns out there was a TSB on the small circle round pieces that the parking sensors are mounted inside of being wrong / bad. They replaced all of those and it fixed the problem.

Turns out it probably isn't that - the port is completely clear and brand new looking. No water or soap anywhere to be found in it. Will have it back at the dealer next week for a few other fixes, this is on the list to be fixed as well. Even though they said they couldn't replicate the problem last time they had it, but I find that hard to believe since it pops up every time you start the vehicle and every couple minutes thereafter as well....

I'll check on this - I go through drive-thru car washes almost daily, maybe soap/water got sprayed up in the plug port. I'll check it out, good looking out man! But beyond that, you've never seen the "rear park assist off" message pop up at all, not a single time other than trailering? (identical to Paul Bergeron's image above). I ask because I was digging through the manual last night wondering if by chance maybe it pops up when you go above the 5mph limit or drive forward or something to deactivate it. But sounds like it shouldn't even be popping up then judging by your wording....

Looking for answers as well, I have same message as you. Vehicle is 2021 Sierra 1500 Denali. Brand new. Has about 200 miles on it, has done this since I purchased it. Vehicle is completely clean, no debris, no water, so soap. Works once in a great while, but this "Rear Park Assist Off" pops up in the display almost every time I drive the vehicle, from seconds after starting it.

If you're saying this as a blanket statement, you're incorrect about your assumptions. There are many aftermarket units that will retain/store the OEM vehicle information, settings, communications etc. There may not be one available for this particular model OEM head unit yet, but there will be at some point. I've had probably 5 or 6 different vehicles that I replaced OEM head unit / brain in and maintained all OEM functionality of things still (not just base model trim units, but highest level trims). They usually cost ~$2k for that level of integration / functionality, but it's usually worth it to me depending on what you're looking to do/add/change. One time I did it simply for the upgraded screen resolution.

That's a very extreme action to take given he said his vehicle is only 5 months old. I actually do sympathize with him - GM delivered a product with a functionality that didn't work correctly on delivery. That's on them to fix it, just as every single other manufacturer has done for their vehicles (and even GM, but I suspect this is an outlying case?), not on the buyer deal with it. The vehicle does not perform to OEM operational standard, ergo it's a defect and covered. Btw - I also know this because I had the same issue with my truck I just got 3 days ago, but I noticed the problem right away upon delivery and they took it back to service and flashed/updated it right there and then. No charge. Said it was under warranty (as it should be).

Update - vehicle was delivered to dealership on the 18th as GM stated, and I took delivery on the 19th. No markup beyond what price I was told, rebates were still on it etc. No issues. My dealer did have allocation when we ordered, and he definitely was intimately familiar with which features/accessories would cause delays. If you walk in to order and just say I want A/B/C regardless of status, you're very likely to experience delays. Mine was 2021 Black Sierra 1500 Denali 6.2, carbonpro, every package.

Ordered a 2021 1500 Denali 6.2 with every option (minus accessories) Order date: 3/15 Accepted: 3/16 Original TPW: 5/10 Updated TWP on 4/23: 4/26 Completed and shipped end of 4/26 week (don't know which day, is on train in transit as of 5/5) Told will be ready for pickup at dealer (in AZ) on 5/18 by both my sales/dealer and CS. FWIW.