Volvo: check engine light, small tank, tank fuel

Question
my check engine light comes on. had a diagnostic device put on it and was told i needed to replace the gas cap. i replaced it and the problem still exists.

Answer
Linda,
I am not sure of the year and model car you have, but there is not a code specificly for the gas cap. There is a code for small tank leakage that could be the cap or a small vapor hose that has a crack, a crack in the tank, fuel pump body cracked, loose gas cap. Go to a shop that knows the Volvo so they can test and pressurize the system and find the fault.