I recently had my 06 XC90 2.5T w/64K miles on it at the dealer due to a check engine light and was informed that the codes were ECM-439C (Fuel tank system, leakage. Major leak) and ECM-4360 (Leak diagnostic unit. Faulty signal) They said that I need to replace my "Leak Detection Pump." I asked about any software updates because I have read that this was a problem and was fixed this software. He said that there are no updates for my car available....that all have been applied. My question is where is this "pump" located and is it a DIY job? They want to charge me $400 to replace it.