Leak Diagnostic Pump Question

[otis44]

06 S60 T5, the car has a CEL (don't recall the actual code) that points to the leak diagnostic pump. I reset the CEL after tightening the gas cap and the light reemerged. Is the pump normally faulty or is there a line leak or similar that causes this issue? Also, has anyone changed one of these and do you actually have to take apart the exhaust, and remove the rear inner fender to access the pump? I haven't been under the car yet and quite frankly am not looking forward to doing so. Thanks in advance