Twingo intake air temperature sensor fault

That sounds like a pain. What kind of temperature reading are you getting from the sensor with your diagnostic tool? Is it reading something completely out of range, like way too high or way too low, even when the engine is cold? Also, did this happen suddenly, or did you notice the performance gradually decrease over time?

Thanks for your input! The temperature reading seems stuck at a very low value, even after the engine warms up. And yes, the performance decline seemed rather sudden. What does that signify?

If the temperature reading is stuck at a low value, even when the engine is warm, and the performance dropped suddenly, it really does point to a faulty intake air temperature sensor. While you could try checking the wiring to the sensor first, it's likely the sensor itself has failed. Replacing it would be the next step, or you could take it to a workshop.

Many thanks for your help; I really appreciate it. I took it to my local mechanic, and as you suggested, it was indeed a faulty intake air temperature sensor. New sensor and labour ended up costing 155€. The Twingo runs like new again!