Tiida Injection Fault

Sounds familiar. I had similar issues with my 2018 Opel Astra, also gasoline. Reduced power and rough idling were the first signs, and it was a faulty connection in the injection system, near an injector. Did you smell fuel near the engine, like a leak?

I didn't notice a fuel odor. Would a fuel smell always indicate a leak, or could a faulty connection exist without it? What else can I check before going to a mechanic?

A fuel smell is a strong clue but not always there. Think of it like a leaky faucet – sometimes it drips, sometimes it's just condensation. Since you checked for leaks, it's likely an intermittent electrical issue with a connector. Without special tools, it's hard to pinpoint. I'd advise a workshop diagnosis before further damage.

I appreciate the advice. I'll book a workshop appointment. The repair was 95€, the cable connector was indeed faulty. Thanks!