Glad to see things are starting to go your way. A bad sensor can affect other sensors by dropping the input voltage throwing other sensors off.
556 is Fuel pump relay primary circuit fault – Power / Fuel Pump Circuits This should be the power TO the fuel pump Relay in the under hood box. check the connections where the relay plugs in for: Power, Overheated connector which has loosened and melted wires, Fuse, Bad Relay, etc. A working fuel pump system will have ECM run the fuel pump for about 2 seconds when the ignition is turned on.