Nissan Sunny check engine light air valve hose

If the check engine light is on, that could be a number of things. Is the engine stalling or idling rough? Perhaps there's an issue with the throttle body or the manifold pressure. Have you checked the vacuum hoses for any cracks or disconnections?

The engine isn't stalling. Could a minor vacuum leak really trigger the check engine light? Seems like a lot of fuss over something small!

While the engine not stalling is positive, even a minor vacuum leak can trigger the check engine light. The system is quite sensitive. Without further diagnostics, it's difficult to pinpoint the exact cause. Considering the symptoms and your suspicion of the air valve, I'd advise having a workshop take a look. It's best to avoid guesswork.

Took your advice and brought it to a workshop. I was right about the hose. The repair cost me 175€. Thanks again for confirming my suspicion, it helped me approach the repair with confidence.