Mini Cabrio preheating lamp issue

The symptoms you describe are quite similar to an issue I encountered with my previous vehicle, a Renault, although the brand is different. A defective heating element can indeed cause those problems. Have you checked the voltage at the glow plugs? A faulty relay or even corroded connections can prevent them from receiving power.

Thank you for your quick response. Regarding the voltage at the glow plugs, could you elaborate on the process of checking this? Also, are there specific voltage readings I should be looking for?

Indeed, confirming voltage at the glow plugs themselves will tell you if the control unit is even sending power. If there's no voltage when the engine is cold and the preheating system should be active, it points towards the control unit or its wiring. However, proceeding with a workshop visit for a proper diagnostic test is advisable to avoid potential further complications. Stalling is not an issue you want to have.

I appreciate your input. A diagnostic test confirmed the glow control unit was defective, likely due to a faulty cable connection as you suggested. Replacing the unit, including labor, cost 95€. The preheating lamp now switches off as expected and the engine runs smoothly.