P0190 - Trying to distinguish sensor / wiring / PCM fault

Question

Engine Systems Fault comes up and engine stalls (This only happens at idle so far). Diagnostics report P0190. This maybe unconnected but the Radio has just mysteriously stopped working, it is lit up and responds but only light volume level coming out.

I want to know what practical test\'s i can carry out to test the sensor or the wiring.

Is there a way of measuring the voltage drop to this sensor without disconnection i.e is there test points (ford Focus C-Max 1.8TDCi)I have this code and am trying to differentiate between the sensor or the wiring.