On the OPEL CORSA D with the Z12XEP engine, the BOSCH MOTRONIC ME7.6.2 ECU is installed .
On this ECU, the crank-shaft sensor is connected with an offset of +2.5 volts.
For MOTRONIC ME7.6.2 the reference voltage is +2.5 volts.
This is what the synchro signals on the Z12XEP engines look like :