W204Man

So I got a Gas Cap loose Message and I checked cap and it was on? I took it off and put it back on but still had the message? Its been a mouth and my check engine light is still on and the “Gas Cap Loose” message pops up about once a week. How can I fix it?
On a side note I saw the new cla 250 looked really good!

Elto

Remove o-ring from cap and check for damage, you can then clean it and when installing it flip over the o-ring.