The car was my wife's until 110,000 miles and then I took it over. The car has always been well maintained and It now has almost 150,000 miles (not much for a Volvo). My other Volvo's were always driven close to 200K miles and left my ownership still running.

About a week ago I got a Check Engine light. Had the codes read.
P2187 (Lean); PO571 (brake switch A circuit ?).
Today, While driving I got a stop immediately message and the dashboard
instrutation went out. I pulled over shut the engine off. When I started the car the message was gone and the car braked normally, as I continued towards home.
A few miles later, I felt a solid bump from the power train and the message was Transmission Service Required. I limped the car home.
Today, I carefully drove the car around the neighborhood, no check engine message, but the transmission service message was on. The care drove and braked normally.
The questions:- what does code PO571 entail
-Looks like I have an ABS module issue and I have no idea what the transmission issue is about.
-The car is almost 18 years old, is it overall time to "shoot it." ???
I will take to my mechanic and get his est. of what's going wrong and is it reasonable to bare the costs of fixing.
Open to thoughts on the above.
Thanks.