S60 rough idle defective connection

Greetings. It sounds like you're experiencing classic symptoms of a defective engine mount. Given your description of uneven idling alongside a stored error, it's highly probable that the cable or plug connection of the component is defective. Have you inspected the transmission mount or rubber mount for visible signs of wear or damage, such as cracking or excessive play? Also, examine the mounting bracket itself. Any unusual vibrations, especially during acceleration or deceleration, could further indicate mount failure.

Thanks for the reply! I haven't actually gotten under the car to look yet, but I will now. When you say 'cable or plug connection', could that really cause the uneven idling too? I was thinking a bad connection would just throw an error but not make the whole car shake!

Indeed, even a seemingly minor cable or plug connection issue can significantly impact engine performance. In modern vehicles, sensors provide feedback to the engine control unit (ECU) regarding engine position and load. A faulty connection can disrupt this feedback loop, leading to incorrect fuel delivery, ignition timing, and ultimately, uneven idling. Given the potential complexity, I strongly advise consulting a qualified technician for a comprehensive diagnosis and repair to avoid potential safety concerns.

Just got back from the workshop, and you were spot on! Turns out it WAS a defective cable or plug connection of the component. They replaced it for 95€, and the car runs like new again. Thanks so much for the help!