Close the knob clockwise on the gas cylinder and unscrew the regulator hose from the cylinder using pliers.
Lift the cylinder by the handle using the weigh scale. If the scale registers empty, the Char-Broil grill is not heating up because you are out of fuel and need to buy propane gas. Take the cylinder to a propane dealer for a refill or a fresh tank.
Reconnect the regulator hose to a full tank of propane. Leave the valve knob on the tank closed for now.
Raise the Char-Broil cover and remove the cooking grates. Take out the lava rocks or ceramic briquettes, depending on your model, and set them aside.
Poke a metal skewer into each of the holes around the circumference of the burner inside the Char-Broil to remove dirt and grease that may be clogging the burner and preventing flames from heating the lava rocks or briquettes.
Pull the burner nozzles out of the venturi tubes on the underside of the grill. The venturi tubes connect to the valves on the back of the grill's control panel. Poke inside each tube with the metal skewer to remove blockages. Spiders are fond of nesting in venturi tubes and their webbing can clog the flow of propane to the burner, preventing the grill from heating up.
Open the gas valve knob on the propane cylinder and turn the burner control knob on the Char-Broil to the "Light" position. Press the red igniter button to light the grill.
Shut off the gas once more and unscrew the regulator hose from the propane cylinder with pliers if the Char-Broil still will not heat up. Disconnect the hose from the back control panel of the grill.
Attach a new regulator and hose assembly to the propane cylinder and the Char-Broil, tightening the connections with pliers. Over time, a propane pressure regulator may become clogged or locked up internally. When this happens, replacing the part is the only way to restore gas flow to the Char-Broil.