Im going to assume the code you have given is PO740 on the obd2 scan tool? PO740 is a TCC circuit malfunction
what does P0650 mean on a 2001 buick century
If you mean pcm- the computer.
02 sensor problem
When the trac light is off, on a Buick Century, the traction control monitoring system is disengaged. It is recommended to have the trac system engaged on wet roads.
Check spelling you mean petcock it's on the bottom of radiator
Trouble code P0730 means:Incorrect gear ratio
If you mean size than 5.25 in front doors, 6x9 in back
Could be a bad alternator. Got to Advance Auto parts store, or any parts store and they may diagnose it for free.
Trouble code P1860 means: TCC PWM Solenoid Circuit
Coolant not reaching temp required. Usually it's sign of bad thermostat.
I'm assuming by petcock you mean the drain on the radiator. If it has one (which it should), It's on the bottom, rear, drivers corner of the radiator.
Trouble code P0442 means:Evaporative emission control system leak detected (Small leak)