I got hit with this message today - All Wheel Drive System Problem (photo'd below) - a few minutes after starting / driving in my 2020 RDX AWD. Turning the car off / on made it go away and the car is driving fine now. I replaced the rear diff fluid about a month ago and its got at least a few hundred miles on it since then. I got under the car today and no signs of leaks. I did not check the level as I do not have a replacement crush washer, I'll pick one up tomorrow but I am nearly certain the fluid level is fine.

Looks like there is a TSB on this issue: MC-10177397-0001.pdf

I need to confirm the DTC code that popped up but I am unable to find it. I hooked up my older (7 years+) bluetooth OBD2 dongle and the app on my phone was able tor read metrics on the car running but was reporting there were no current or historic trouble codes. Any suggestions, do I need a new dongle? Should I try to find someone with a pro scan tool?

 

You might need a more professional or the dealer to read the codes. I had a 2021 that had that rear diff solenoid issue. At the time I took it into the dealer to have it addressed, the light was off, but there was a stored code for it. When mine failed, I was at about 5,000 miles on mine.