Vios hard start and stalling

I had similar symptoms with my Vios. Check engine light, poor starting, occasional stalls. It could very well be related to the camshaft position.

Interesting. When you say 'camshaft position', are you referring specifically to the camshaft sensor itself, or some other component in that area of the engine control system? Was there any specific diagnostic code you recall?

Yes, it was the camshaft sensor. It impacts ignition timing. I'd recommend taking it to a workshop to get a proper diagnosis. In my case, it was the sensor itself.

Thanks for the confirmation. I took it to my local shop, and indeed, it was the camshaft sensor. The encoder wheel was also defective. The repair cost was 695€. All seems to be running smoothly now.