So, almost a year after I replaced the 2nd Air sensor, the SES came back last month. Went to Autozone, same code P1419. Maybe it's a winter routine. Or could be the valve needs to be cleaned or just needing a new valve. I find it hard to believe the sensor lasts only 10-11 months.

Coincidentally is that every time I do something proactive, ie: replaced the O2 sensors a week or two before this SES light went on, I get something discouraging. My X5 just made to the 100K mark so I thought I'd take care of it.

Oh yeah, I also replaced the Spark Plugs and that does seems to restore a bit power lost over time and reduced the quick/sudden acceleration that I've experienced sometimes.