The CNG Pressure Gauge Sensor gives electrical output to the LED Indicator depending upon the pressure in the Cylinder / bank-cylinders. When the CNG Pressure inside the cylinder is above 160 Kg/Cm², all four Green LEDs will glow. As pressure reduces, the no of Green LEDs which are glowing reduces. When CNG Cylinder pressure drops below 40Kg/Cm², all Green LEDs will stop glowing and Red LED will glow indicating that refilling of cylinder/cylinders is required.