CMAX rough idle and power loss

A mixture preparation error with those symptoms on your Ford CMAX suggests a few possibilities. Have you checked the oxygen sensor readings? A faulty sensor can cause the engine to run rich, leading to catalytic converter issues down the line. Also, inspect the mass airflow sensor and the intake manifold for any leaks or obstructions, as these can also contribute to incorrect air-fuel mixtures.

Thanks for the quick reply. Regarding the oxygen sensor, how can I check its readings effectively? Is a standard OBD2 scanner sufficient, or do I need something more specialized? Also, could a faulty injection valve/injector cause these issues?

Yes, a standard OBD2 scanner should provide sufficient data to assess the oxygen sensor's performance. Look for values that fluctuate as expected. Static or erratic readings indicate a problem. Regarding the injection valves, a defective injector is indeed a likely cause given the symptoms you describe. Considering the complexity, I would recommend a thorough diagnostic check at a qualified workshop.

Understood. I appreciate the advice. I'll take it to a workshop for a professional diagnosis. Turns out it was indeed a defective injector, costing 515€ to repair. Thanks again for pointing me in the right direction.