I turn on graphs and compare the two sensors.. After having the engine run for a while to heat things up sensor one is a 0.5ish volts like its supposed to. But sensor 2 just reads a steady 0.056 volts.
Just so I understand you've got the engine good and hot? By the way what car/engine is this, not that it'll make much difference to the O2 sensor outputs. Then you've got
MES plugged in and you're looking at the graphed pre and post cat voltage outputs?
If this is what you're doing the pre cat sensor should be switching somewhere around 0.8/0.9 volts to 0.1/0.2 volts and back again roughly once a second. I find frequency and exact voltages vary but broadly speaking you should be seeing this. Speed the engine up a bit, say to 2000 rpm and hold till you see the trace alter - the frequency should increase (that is it should switch more quickly). If, as you say, it's holding a constant 0.5 volts that's not right.
The downstream one should hold a steady (or almost steady) reading. Around half a volt would be good. If the CAT is good it will not oscillate.
The precat sensor has quite a marked effect on fueling so if, as you say, it has a steady output and shows no tendency to switch or to only switch slowly with reduced amplitude it may well be your problem. It's worth mentioning that most (the Zirconia type) oxygen sensors are best thought of as little batteries. Although the heater in it is powered from the vehicles battery the signal voltage is produced by the sensor itself. The Japs were very keen on Titania sensors which act like a variable resistor and I believe you can come across them in euro vehicles especially very new ones. I think there is also a new "wide band" type now on the go too which I know nothing about at all. Good reason to stay with older cars say I!
Hope some of that is helpful. Interestingly our little Panda has a precat sensor which is working fine but a post cat sensor which, although giving a straight line output, is right up at the 0.9 volts. This would indicate an absence of oxygen so "rich" mixture which makes no sense if the upstream sensor is working OK and the CAT emissions passed on the MOT not so long ago. I suspect the sensor may be goosed. Going to take it out and test it with a flame just like you. The car is a bit "dull" on the acceleration but I didn't think the post cat sensor had much effect on fueling so I'm a bit puzzled.