I had a similar problem with my S60. The dealer replaced a part - some kind of relief valve, I believe - under the CPO warranty. It was three years ago, so I can't remember all the details. They had to remove the fuel tank to do it, after removing the custom trailer hitch that was in the way. No complaints, they just needed to re-schedule the work because the hitch R&R was going to add time to the job. Only cost me the deductible, and the warranty also paid for a rental car.