Device for detecting the state of a fuel injector

A device for detecting a state of a fuel injector, the device comprising:

• an injector for injecting fuel into an engine combustion chamber,
• a switch which is formed by an injector housing and an injector nozzle needle and changes its switching state depending on a closed or open state of the injector,
• an input line for supplying energy to an actuating element which adjusts the injector nozzle needle in its two states,
• an output line for conducting energy away from the actuating element, and
• an evaluation unit for detecting the switching state of the switch,
• wherein
• a first switch contact of the switch is connected to an electrical input line of the injector,
• a second switch contact of the switch is connected to ground, and
• the evaluation unit is configured to carry out a signal measurement in order to conclude a switch state,
• comprising
• a signal filter comprising only passive components and connected between the evaluation unit and the input line and between the evaluation unit and the output line of the injector in order to emphasize a signal generated by switching the switch.