I own a 2001 V70 XC with approximately 50,000 miles. Recently the "Check Engine" light has come on and the message panel reads "Emissions System Service Required". My mechanic checked out the car and said it was probably caused by the gas cap not being tight and therefore caused a depressurization. He cleared the message board and sent me on my way. Two days later the same messages have reappeared. I called my mechanic and he's doing some research. Whatever that is. Any Advice?

Have the throttle body cleaned good and have the evap valve checked then see what happens from there.It might be a bad throttle body.But have it cleaned first.