Toyota iQ reduced power and fuel consumption

Hey, that sounds like it could be a few things. Is it running rough, or just down on power? Have you checked for any obvious things like loose connections or anything around the sensors? It could be a cam sensor issue, and that might affect the engine synchronization. Maybe even the timing chain? What codes are you getting?

Rough, yes, a little bit, but not too bad. Where exactly is the crankshaft sensor located? Is it easy to reach? And if it is the crankshaft sensor, would that explain all the symptoms, even the fuel consumption?

Okay, so a rough idle too points more towards sensor or timing issues. The crankshaft sensor is usually near the crankshaft pulley, sometimes a pain to get to. And yeah, a faulty crankshaft sensor could definitely cause all those symptoms, since it messes with the engine timing and fuel injection. But, without proper tools I would advise you go to a workshop. Does 340€ sound about right?

Thanks for the help! You were right, turned out to be a defective crankshaft sensor. Got it replaced at a workshop for 340€ and everything's back to normal.