RE: FAULT CODE P1647
Bank 2 is the bank closest to the radiator. The first thing I would check is the wiring to the sensors for that bank. The harness connectors for both the upstream and downstream o2 sensors are connected to a sheet metal bracket in front of and below the battery. The connectors should be attached to the bracket and the wiring should be routed through a clip arrangement attached to the cooling fan shroud. If the harness has become displaced from the clips on the shroud or the connectors are displaced from the metal bracket the wiring can be fouled by the fan. If that checks o.k. check the fuses for the o2 sensor heaters. I don't have an electrical guide in front of me but I believe the fuses ar in the underhood fuse box, just check them all.