Gilly

I  bought my first Subaru about a month ago! It's a 2002 Outback 3.0 Australian model. However, there are a couple issues that I have been trying to track down. 

1) The guy I bought it from told me that the O2 sensor had just been replaced and that the CEL needed to be reset. I reset the light but it came back immediately. It is a P0031 and P0051 which is the heater circuits for the front sensors. I believe that they were new sensors but they were a cheap brand so I sourced some OEM (which is Denso, right?) sensors from a junk yard. I still have the same problem. I checked as many grounds as I could fine and they all seemed pretty clean. Now I'm wondering if it is a relay. I have been looking over the manual a bit but I can't decipher which relay controls the heater circuit. Does anyone know or have other suggestions?

2) The other issue is the ABS and VDC lights on the right hand side of the dash are on. I was on a rough dirt road a few days ago and the two lights on the right side of the dash turned off and the "VDC OFF" light on the left hand side of the dash came on. To me that means it probably isn't an ABS sensor but I'm just guessing. The guy I bought it from told me it needed a new VDC control module but I can't find much info on that or where it is. I was wondering if it is integrated with another computer somewhere. Any ideas?

Unfortunately in Australia I can't finish registration without these issues fixed. Any help is greatly appreciated.

-Tyler