Freestyle fuel tank ventilation leak

It could be related to the fuel tank ventilation system. The symptoms match a potential leak. Have you smelled any fuel, especially after filling up? Is the check engine light always on, or does it come and go? A bad purge valve could also cause this. Has that been checked?

Thanks, I'll check for fuel odors next time I fill up. The check engine light has been on constantly. I haven't checked the purge valve. Can I check that myself, or should I take it to a professional?

Since the check engine light is always on and you haven't smelled fuel, the issue might be the activated charcoal filter. You can test the purge valve, but it needs special tools. Given the age and mileage, I'd suggest a workshop. They can do a smoke test to find the leak in the fuel tank ventilation system.

Thanks for the advice. The workshop did a smoke test and found a leak in the fuel tank ventilation system, caused by a bad activated charcoal filter. The repair cost 275€. Thanks for pointing me in the right direction!