I first noticed my problem during the ascent on a day when the traffic was in stop-and-go mode due to an accident. I've since seen it in other stop-and-go traffic on the flat (San Jose spends a lot of time doing stop-and-go on the freeways).
Symptoms occur during automatic shifts - I think between 1st and second, but it may happen between 2nd and 3rd as well.
- RPM flare during down shift followed by sharp grab (as if it slips into neutral then engages at too high RPM) on both up and down shifts
- Jarring up shifts between 1st and 2nd - no obvious RPM flare.
- Apparent brief 'drop out' of gear and grab back when crawling.
I consistently get a very hard grab when shifting from reverse into Drive (such as when reversing out of the driveway and changing gear to pull off). I can avoid this by pausing in Neutral for a few second between reverse and drive.
Traffic is always horrendous and dangerous when these things happen so I haven't been able to focus on the instruments to characterize it thoroughly.
I took it into my specialist after the first occurrence (trustworthy and worked on my cars for 17 years, and there's no Volvo dealer in my city).
No codes found. But they did a full CAN-bus update to ensure I had all the latest firmware in the ECUs. Nothing for the transmission, but the ETM got updated. We also reset the adaptation. I've done easily 500 miles since then, so it's had time to adjust.
Oh, and this morning I got the "Reduced Engine Performance" message when I first started her. A restart a few minutes later did not re-trigger it, and I've not seen it since.
Before I take it back again, I'd really like some good hypotheses to explore.