FLE-P type EMULATOR restores the correct fuel level readout in vehicles powered by LPG/CNG which are equipped with on-board computer, ECU. LPG/CNG installation in vehicles with on-board computer may cause some disturbance with the petrol level indicator because this function is based on the distance traveled and the exploitation conditions (in vehicles NOT equipped with on-board computer, only with the float switch in the tank). Regardless that the vehicle travels on gas, the on-board computer incorrectly signalizes petrol usage which confuses the driver and prevents the accurate assessment of actual petrol level. Installation of FLE-P EMULATOR eliminates the problem and corrects the ECU readout.