Thalia Misfire Diagnosis

I also drive a Thalia/Symbol. I had very similar symptoms not too long ago: rough running, engine light, the whole shebang. Have you tried checking your ignition coils? That's where I'd start, as it's cheaper than replacing a fuel injector.

Interesting! When you say 'ignition coils', did you have the same Cylinder misfire code? How did you check them?

Yes, I remember the error code indicated a cylinder misfire. I lacked the tools and expertise to check the ignition coils myself, so I took it to a mechanic. They used diagnostic tools and found the injection valve was defective.

Okay, thanks! I took it to the shop, and you were right about the injection valve. It was defective, and replacing it fixed the problem. Cost me 515€, but at least it's running smoothly again!