Seicento stalling idle check engine light

The symptoms you describe, particularly the stalling at idle and the check engine light, combined with the potential link to a full fuel tank, do suggest a possible issue within the fuel tank ventilation system, often referred to as the EVAP system. A defective activated charcoal filter can certainly cause pressure imbalances within the fuel tank. However, before jumping to conclusions, have you noticed any unusual hissing sounds coming from the fuel tank area, particularly after a long drive? Also, is the check engine light constantly on, or does it come and go?

Okay, thanks for the info! I haven't noticed any hissing, but honestly, my hearing isn't the best. The check engine light is intermittent; sometimes it's on for days, sometimes it goes off for a few hours. What's the charcoal filter do exactly? I mean, how can that cause the engine to stall?

The activated charcoal filter is a crucial component of the EVAP system. Its primary function is to capture fuel vapors that evaporate from the fuel tank, preventing them from being released into the atmosphere. When this filter becomes saturated or defective, it can restrict the proper airflow within the fuel tank. This restriction can lead to a vacuum build-up as fuel is drawn out, potentially causing the engine to stall, particularly at idle. Given the age of your vehicle and the intermittent nature of the light, the most prudent course of action would be to have a qualified technician perform a smoke test on the EVAP system to pinpoint the source of the leak with certainty.

Just wanted to say thanks for pointing me in the right direction. I took it to a local garage, and they confirmed it was the charcoal filter. Replaced it, cost about 275€ with labor, and the check engine light is finally gone. No more stalling either! Appreciate the help!