The P0463 code means high voltage is sent to the ECM from the fuel level sensor. If the new fuel level sensor is good and there is no CAN communication code being displayed, than the problem is either in the Unified meter and A/C amp assembly or in the harness and/or connectors of the fuel level sensor circuit. The diagnostic procedure is on page EC-469 of the of the 2006 Murano factory service manual. You can get here in the site's "Knowlege Base" section. It's located in the "Engine Control" chapter:
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