Volvo S70, 1999, P1603, P0172, P1171 codes, PLS HELP

[subbarao]

Ok,
couple of months ago, I kept getting hte P1603 and P1171 codes. I replaced the MAF sensor, and it was gone. Noew those codes are back with an additional code, P0172. What do I do??? Do i replace the O2 sensors? The car was bought with 80k miles on it, it now has 104K. I am not sure if the O2 sensors have ben replaced before or not...just dont want to spend the money at the wrong thing. Any advice is much appreciated.
Happy new years people!

[White850Turbo]

100k miles is about the life expectancy of an o2 sensor. It's a simple job to replace it and if you do some searching around, you can find an OEM direct plug in Bosch sensor for about $100. At the very least, your gas mileage should improve.

[volvo 4 life]

I have this same problem code p1171 and also p1550. I took it to my boss who owns a volvo and toyota shop to read my codes and these too codes I get all the time. We have done a smoke test and I have no leaks but I went down to the local pepboys and got some MAF Sensor cleaner and it fixed my acceleration problem i forgot to mention that I have that and ordered a abs modular. I'll get back if that helps the p1171 code.