check engine light
Bad or loose gas cap common cause
What trouble code do you have? -Jim
You've overfilled your gas tank drowning the charcoal canister forcing the computer to not sense any back pressure, and not able to purge correctly- couple of months with this and the "black tape" solution would be okay, but we'd have to know that this was the only reason.
There are around one thousand engine trouble codes. It could be anything. Get the codes read, write down the number and post it.
Looking for a Used S40 in your area?
CarGurus has 1,054 nationwide S40 listings starting at $1,400.
Search Volvo S40 Questions
Volvo S40 Experts
Related Models For Sale
Used Cars For Sale