Fixing up a 2004 Outback, where to start?

2004 Subaru Outback, 2.5 manual transmission. This thing hasn't had much in terms of maintenance over its life, but the PO did supposedly change the timing belt 10k miles ago and it looks to have new plug wires. My younger but not young sister (39) bought this car at a dealership last year with 120k miles on it and it sits all summer while she drives her diesel Jetta and when the snow flies the Outback hits the road till spring. It's been sitting all summer and she dropped it off at my house to work on since when she did fire it up recently she got a CEL.

 

So I start going over the car and notice:

 

• It has a torn front right inner CV boot (no noise from it yet-appears to be a recent tear) Grease has been slung all over the place including on the catalytic.
  

• It made a massive clanking sound when you turned into driveways etc. which I traced back to a broken swaybar link.
  

• The rear brake rotors where rusted up and grooved something fierce. The pads appear to have very little contact area.
  

• The belt slips on the power steering pump (despite being tight) when you turn the wheel with the car stopped. (when parking etc.) I checked the power steering fluid and it looked like flat cola so I drained that out and refilled it, ran it, drained and filled it again and it might have helped some.
  

• Last but certainly not least the Check Engine Light is on. OBD reader says it is a P0139- "Oxygen sensor circuit slow response bank 1 sensor 2." ??So that's the downstream sensor on bank 1? Which bank is that?
  

So I've ordered parts to fix all of these things, but I thought it would be smart to ask "what else?" What else should I do while I have it in my posession to help extend its life and keep it reliable? Change oil in the manual trans and rear end? Are there other things that go bad that I should look over? How hard is it to replace the struts?

 

Sorry for the long post and many questions! Thanks in advance for the wisdom!

New servo steering belt seems to be on the list. Replace the alternator belt too while you are at it and check or possibly replace the pulleys.

 

At that distance - a thorough check of the injectors.

 

As for the O2 sensor, depends on how many sensors you can find, it's always a tricky sport to get the right one, but if there are only two I would say that it's the post-cat O2 sensor.

 

But searching the web a bit reveals that it's the post-cat sensor: http://engine-codes.com/p0139_subaru.html

The PO139 showed up on my Impreza two or three times over a period of several months. I deleted the fault code each time to see how quickly would come back and after a couple of deletes the problem did not reoccur. Because the CEL quit showing up, I didn't bother to repair it and the car's run fine for years. The car passes inspection and get reasonable gas mileage, so it seems like there was not really a problem.

 

Maybe try deleting the code a few times to see if it is a false alarm?

Thanks gents. I dropped the 100 bills for a new rear O2 sensor for a couple reasons. First I already had the pass side inner axle disconnected (replacing the torn boot-cost around $6) making access a breeze and second I wanted the peace of mind of knowing I wasn't going to kill my cat or something. Started it up and CEL is gone. now I can get a new state inspection etc. Thanks again.