Lamnda fault bank 1 fault?
 

Lambda sensors are O2 sensors, so, yeah, replace it.

Which one both or just the upstream one?

Depends on which one is giving the fault. You need to have the codes read -- that will tell you where the problem is.

If you have a scan tool, check out the live data on the O2 sensor output. I found one to be at a static voltage, usually around 0.452V and replaced it after a fault code came up. Still the same problem, turned out the ECU ground appeared to be faulty. Dig around, there are threads on here about this.

Check the O2 sensor voltage locally if you can, it should cycle up and down between 0 and 1 V. If it is doing that and the live data is static you can create a local ground like I did and all has been well since. You may well have to wait until the engine is warm enough. It was a pain in the arse for me as I had to get the old one cut out and a new piece welded into the exhaust to take the new sensor.

Watch out you don't burn yourself on the exhaust though!

Data stream o2 sensors
 

Ok so I hooked up my scanner and got a reading of 10.29 upstream sensor driver side and 4.9 down stream. Can anyone tell by these numbers which sensor is the culprit :)

Just read the OBDII codes. The error code indicates the specific sensor.

Yes, sorry didn't mean to open a can of worms with my post. Hopefully your sensor is caput and you simply take it out unplug and install and away you go. I did this and still had the problem.

The fault codes should tell you the sensor.

Ultragauge will show this too.

Here is snip from a video I made to show the sensor readings. The engine is off here so they all read 0.45ish V. Once the car heats up and the loop is open they will all cycle up and down. My B2S2 sensor continued to read 0.452 or thereabouts. Once I grounded it after much research, the cycling came back on that sensor.


https://cimg0.ibsrv.net/gimg/landrov...8439fe5928.png


Disclaimer.. because I was working on the CDL transfer case at the time I had good access to the rear sensor wires, which I studied from the RAVE electrical and cut back the insulation on some wires so I could measure the voltages before the ECU. That's when I found out the sensor was actually working but the ECU was not detecting it. I even measure at the ECU entry which is a pain. Don't take my advice and screw with things if you are not comfortable.

I would but cleared codes
 

So wait until it comes back. You might be lucky and it was just a glitch.