An inlet pressure fault usually means the instrument cannot hold the setpoint. Routine causes are the gas supply turned down or empty, a septum leak, a column ferrule leak, a column that is broken or not installed, a plugged split vent trap, or column dimensions in the method that do not match the column in the oven. Electronic pressure control calculates flow from those dimensions. Wrong length or inner diameter produces the wrong pressure.
A detector pressure fault points at makeup gas, FID hydrogen or air, or the detector gas fitting, depending on the detector. Read the message. Do not swap gases to “see what happens.”
If the system shuts down on a leak, or if you smell gas, ventilate, stop, and call Mahut. Never use a flame to find a leak. Hydrogen collecting in an oven or a closed room is a fire hazard.