Okay I watched a vid today explaining how to test your O2 sensors, very easy, link is here:
Anyway, after the %&$* bastards at Nissan Nelspruit told me my sensors were checked and are ok, I decided to check them myself as I was sure my patrol was overfuelling. Turns out both were stone dead, one's wires were even without insulation anymore, so ZERO signal getting to ECU from that one, other one reached a max on 0.2V where they should get to 0.9 to 1.0V. Anyway, I went to Bosch Diesel, and bought 2 universal sensors from them, but here's the catch, and the purpose of this post:
The ones you get at Bosch, are 4-wire, the ones that come off the troll are 3 wire. They told me the 3-wire we'll only get from the stealers. Anyway, the 4-wire sensor works. The extra wire (grey in colour), is just an external ground which I soldered together (one each from each sensor), then to a single wire lead to earth on one of the component mounts in the engine bay. The 2 white ones join to 2 white on the new sensors, and black to black. Simple as that.
Thought I'd let you guys know so you don't get disheartened and go buy from the dealers for like R7k per pair.
We need to get innovative on checking and solving our own issues guys, and sharing results. I went to Steves Auto in Nelspruit and was told I need a chip and freeflow. WTF!?
Engine idles much smoother with new sensors installed, will test drive to town tomorrow, and run a few tanks to see if consumption improves any. After cleaning MAF sensor and reversing the PVA mod, my consumption (for highway only on this occasion) ran 6.46km/l over 560km. Felt great, tank was on half after 560km!! :)