Astra engine stalling

Those symptoms certainly point towards a potential issue within the fuel tank ventilation system. The check engine light illuminating, combined with stalling at idle, suggests that unmetered air may be entering the engine. This often happens due to a leak somewhere in the system. Has there been any recent work done on the vehicle? Also, have you noticed any changes in fuel efficiency lately?

No recent work, and I haven't really been tracking fuel efficiency super closely, but it might be a bit worse than usual. What part of the fuel tank ventilation system should I be checking first?

Given the age of your Astra and the symptoms you describe, a likely culprit is a defective activated charcoal filter. This filter is a crucial component of the fuel tank ventilation system, responsible for trapping fuel vapors and preventing their release into the atmosphere. Over time, the filter can become saturated or damaged, leading to leaks and malfunctions. While it is possible to inspect the filter yourself, I'd recommend taking your vehicle to a trusted workshop for diagnosis and repair. They can perform a smoke test to pinpoint the exact location of the leak and properly assess the condition of the activated charcoal filter and related components.

Thanks for the help! Took it to the shop, and you were spot on – turned out to be the activated charcoal filter. Cost me about 275€ to get it sorted, but at least the check engine light's gone and it's not stalling anymore.