Ok, I'll try that on next occasion, and report again.

I overhauled the battery compartment recently, and cleaned and greased the ground connections on this occasion.

The error seems to hint to a) the ground connection of the ECU and b) sensor connection.
What is the relation between these two?

Hello, the Airbag warning symbol lights in the dashboard of my Alfa 159 (model 2008). MES shows this error when reading the ECU: "B1004 - connection to ECU grounding." "ECU supply voltage is below or above specifications." I cleared the error and the light went out - but lighted ...