Mondeo Ignition Error

I encountered a similar predicament with my previous vehicle, a 2014 Opel Insignia diesel. The symptoms you describe mirror my experience precisely. Have you performed a thorough inspection of the starter solenoid and associated wiring for any signs of corrosion or damage? A voltage drop test across the circuit may prove enlightening.

Voltage drop test - useful, but where exactly should I measure?

The voltage drop should be measured across each connection point within the circuit, including the battery terminals, ground connections, and the starter solenoid terminals themselves. A reading exceeding 0.2V typically indicates excessive resistance. However, given the potential complexities, it may be prudent to consult a qualified technician for a comprehensive diagnosis.

It was a defective connector. 95€ repair. Thanks for the input.