Chevrolet Repair: dtc codes, fuel level sensor, upper radiator hose

Question
Van I got a power programmer for a 99 7.4 chevy dually and I got these codes PO 125 (insufficient coolant temperature for closed fuel control)& PO 463 (fuel level sensor circuit high input) what does all this mean? and how do I fix it? Thanks for your time.

Answer
Hi George,
For the temp code, first make sure the coolant level is full....inside the radiator, not just in the coolant recovery tank.
Be sure to check it when there is no built up pressure. I like to squeeze the upper radiator hose to check for pressure.
If the coolant is full, you may want to check the thermostat, or just replace it. it could be stuck open, not allowing the coolant to heat up properly.

The fuel level circuit could be a loose connection to the fuel sender in the tank, or to the back of the instrument cluster. Try just wiggling the connectors.

Van