In some cases its possible for a glitch that trips the EML on, sometimes OEMs bring out software updates to combat these. As you're on Bluefin, is there updates available for your car?

The 02 sensor once in 'closed loop' operation where the ECU is controlling the AFR will go anywhere from 0.2 lean to 0.8 volts rich it alternates between the 2 going from rich-lean with an average of 0.45 for Lambda 1 (14.7:1 AFR)

These voltages can be viewed on live-data on things like the Ford IDS dealer tool which shows them in graphical form.

Or,Ideally an ocilloscope is required.

More reading - http://www.picoauto.com/applications/lambda-sensor.html

Maf sensor operates up to a max of 5 volts but ECUs live data can sometimes show a reading in g/s (grammes/second) of airflow and this can be monitored for a smooth increase up to its peak airflow which can be calculated to a rough BHP reading. (a 150hp engine should show 120 g/s peak)
Not all ECUs support this data though.