Mini Cooper Starting Issue Terminal Ignition Error

A "Terminal 15 ignition positive interrupted" error on your Mini Cooper with a diesel engine sounds concerning. Before jumping to conclusions about wiring, have you checked the voltage at the battery terminals themselves? A voltage drop could cause all sorts of electrical gremlins. Also, when you try to start it, do you hear any clicking sounds coming from the starter solenoid?

Thanks for the quick reply. I don't have the equipment to properly check the voltage, but the battery terminal looks ok to my eye. As for the starter solenoid, I'm not entirely sure where that is located. Could you give me a hint where to find it so I can listen for that clicking sound you mentioned?

The starter solenoid is typically attached directly to the starter motor itself. However, without proper tools to diagnose the voltage and test the wiring, it will be challenging to pinpoint the fault yourself. Given the error code and the reported likely cause, the diagnostic already points towards a cable/plug issue. If you are not comfortable with electrical troubleshooting, taking it to a qualified workshop might be the most prudent course of action.

Just wanted to close the loop on this. Turned out the diagnostic was spot on. Took it to a local mechanic, and they found a defective plug connection as suspected. They sorted it out, and the car is starting perfectly now. Cost me exactly 95€. Thanks for the help!