Devices realized on purpose for simplify the interruption of the injectors on all the electronic injection cars. They allow of detach and emulate each injector singularly, avoiding the lighting of the warning CHECK ENGINE. They avoid any cut of the cables of the original wiring, detach the injector without the addition of other relays, and allow the automatic return to petrol in case of electric damage of the LPG plant. The time of overlap of the fuels, is visible through the proper RED LED place near the TRIMMER of regulation of the overlap time.