Please watch vidoe of trim here: 

 

My long term fuel trim at idle hovers at about -10.9% on average and it goes down when I am driving only - it does not change when I press throttle in neutral - it does not chnage when coasting in neutral - it only changes when I am in motion and press throttle.
I watched few videos saying the O2 sensor should switch on/off but mine seems to appear to stay at 0.8v majority the time. 
Any tips on this issue or is this normal for a Subaru?

Or what other sensors should I be looking at?

Thanks

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