I have someone asking about his Round - he reports: "it comes up - E - then after about 1second goes to - - - and does nothing else"

I have asked if the two red wires are connected correctly (+12v on wideband pn3) and asked him to check that the sensor is correctly located, which he has checked as says it is.

The firmware has not been changed from the version it was shipped with.

What could the fault be?

What other things can we check?