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A method for operating a fuel injection system of an internal combustion engine is described in which pressurized fuel is provided in a pressure storage device and a fuel pressure prevailing in pressure storage device is regulated with the aid of a pressure regulation, during a first measuring inter

A method for operating a fuel injection system of an internal combustion engine is described in which pressurized fuel is provided in a pressure storage device and a fuel pressure prevailing in pressure storage device is regulated with the aid of a pressure regulation, during a first measuring interval at least one fuel withdrawal from the pressure storage device taking place, and during a second measuring interval no fuel withdrawal from the pressure storage device of this type taking place, and during the first and the second measuring intervals a performance quantity of the pressure regulation being ascertained in each case, and the fuel quantity withdrawn during the first measuring interval being ascertained for the at least one withdrawal from a difference of the ascertained performance quantities of the pressure regulation.

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1. A method for operating a fuel injection system of an internal combustion engine, the method comprising: providing pressurized fuel in a pressure storage device;during a first measuring interval: performing at least one controlled withdrawal of a predetermined quantity of fuel from the pressure st

1. A method for operating a fuel injection system of an internal combustion engine, the method comprising: providing pressurized fuel in a pressure storage device;during a first measuring interval: performing at least one controlled withdrawal of a predetermined quantity of fuel from the pressure storage device, thereby causing a controlled change in a fuel pressure prevailing in the pressure storage device;a pressure sensor sensing, and outputting a signal corresponding to, a fuel pressure prevailing in the pressure storage device during the first measuring interval as a result of the controlled withdrawal of the predetermined quantity of fuel;regulating, by a pressure regulation device, the fuel pressure prevailing in the pressure storage in response to the signal output by the pressure sensor during the first measuring interval; andascertaining a performance quantity characterizing the pressure regulation performed in response to the signal output by the pressure sensor during the first measuring interval;during a second measuring interval, during which no controlled withdrawal of fuel from the pressure storage device is performed: the pressure sensor sensing, and outputting a signal corresponding to, a fuel pressure prevailing in the pressure storage device during the second measuring interval;regulating, by the pressure regulation device, the fuel pressure prevailing in the pressure storage in response to the signal output by the pressure sensor during the second measuring interval; andascertaining a performance quantity characterizing the pressure regulation performed in response to the signal output by the pressure sensor during the second measuring interval; anddetermining a condition of the pressure sensor based on a difference between the performance quantity ascertained for the first measuring interval and the performance quantity ascertained for the second measuring interval. 2. The method of claim 1, wherein the at least one fuel withdrawal is performed by activating a servo-valve of an injector of the internal combustion engine so that a control quantity of the fuel is withdrawn, at which the injector does not yet inject fuel into a combustion chamber of the internal combustion engine. 3. The method of claim 1, wherein a servo-valve of an injector of the internal combustion engine is activated multiple times for withdrawing a control quantity during the first measuring interval. 4. The method of claim 1, wherein the first and second measuring intervals are during an operating mode of the internal combustion engine in which usually there is no injection of fuel into a combustion chamber of the internal combustion engine. 5. The method of claim 1, wherein: the regulating of the fuel pressure includes regulating the fuel pressure in the pressure storage device to an identical pressure setpoint value, with the aid of the pressure regulation, in each of the first measuring interval and the second measuring interval;the at least one fuel withdrawal is performed by activating the injector during the first measuring interval so that a control quantity of the fuel is withdrawn from the pressure storage device, the injector not yet injecting fuel into the combustion chamber;the ascertaining of the performance quantity of the first measuring interval includes ascertaining, during the activation of the injector, a first value of the performance quantity of the pressure regulation, which is a manipulated variable of at least one of a pressure regulator and a fuel metering device; andthe determining of the condition of the pressure sensor includes comparing the difference to a difference that had been previously ascertained under comparable conditions and which is stored in a control/regulating unit of the internal combustion engine. 6. The method of claim 1, wherein values of the performance quantity of the pressure regulation are ascertained in the first measuring interval and the second measuring interval both when the fuel injection system is in a new condition and when the fuel injection system is in an older condition, and the values ascertained in the first and second measuring intervals when the fuel injection system is in the older condition are compared to the values ascertained in the first and second measuring intervals when the fuel injection system was in the new condition, and the state of the pressure sensor is deduced from the comparison. 7. The method of claim 1, wherein the performance quantity of the pressure regulation is ascertained at least one of at different fuel pressures, at different fuel temperatures, for different fuel types, and for different activation periods of one of an injector and an servo-valve of the injector. 8. A non-transitory computer readable medium having a computer program, which is executable by a processor, comprising: a program code arrangement having program code for operating a fuel injection system of an internal combustion engine, by performing the following: providing pressurized fuel in a pressure storage device; during a first measuring interval: performing at least one controlled withdrawal of a predetermined quantity of fuel from the pressure storage device, thereby causing a controlled change in a fuel pressure prevailing in the pressure storage device;obtaining from a pressure sensor a signal corresponding to a fuel pressure prevailing in the pressure storage device during the first measuring interval as a result of the controlled withdrawal of the predetermined quantity of fuel;controlling a pressure regulation device to regulate the fuel pressure prevailing in the pressure storage in response to the signal output by the pressure sensor during the first measuring interval; andascertaining a performance quantity characterizing the pressure regulation performed in response to the signal output by the pressure sensor during the first measuring interval;during a second measuring interval, during which no controlled withdrawal of fuel from the pressure storage device is performed: obtaining from the pressure sensor a signal corresponding to, a fuel pressure prevailing in the pressure storage device during the second measuring interval;controlling the pressure regulation device to regulate the fuel pressure prevailing in the pressure storage in response to the signal output by the pressure sensor during the second measuring interval; andascertaining a performance quantity characterizing the pressure regulation performed in response to the signal output by the pressure sensor during the second measuring interval; anddetermining a condition of the pressure sensor based on a difference between the performance quantity ascertained for the first measuring interval and the performance quantity ascertained for the second measuring interval. 9. A control/regulating unit of an internal combustion engine, comprising: a computer readable medium having a computer program, which is executable by a processor, including a program code arrangement having program code for operating a fuel injection system of an internal combustion engine, by performing the following: providing pressurized fuel in a pressure storage device;during a first measuring interval: performing at least one controlled withdrawal of a predetermined quantity of fuel from the pressure storage device, thereby causing a controlled change in a fuel pressure prevailing in the pressure storage device;obtaining from a pressure sensor a signal corresponding to a fuel pressure prevailing in the pressure storage device during the first measuring interval as a result of the controlled withdrawal of the predetermined quantity of fuel;controlling a pressure regulation device to regulate the fuel pressure prevailing in the pressure storage in response to the signal output by the pressure sensor during the first measuring interval; andascertaining a performance quantity characterizing the pressure regulation performed in response to the signal output by the pressure sensor during the first measuring interval;during a second measuring interval, during which no controlled withdrawal of fuel from the pressure storage device is performed: obtaining from the pressure sensor a signal corresponding to, a fuel pressure prevailing in the pressure storage device during the second measuring interval;controlling the pressure regulation device to regulate the fuel pressure prevailing in the pressure storage in response to the signal output by the pressure sensor during the second measuring interval; andascertaining a performance quantity characterizing the pressure regulation performed in response to the signal output by the pressure sensor during the second measuring interval; anddetermining a condition of the pressure sensor based on a difference between the performance quantity ascertained for the first measuring interval and the performance quantity ascertained for the second measuring interval. 10. The method of claim 3, wherein the activation is periodic. 11. The method of claim 5, wherein the pressure regulator is a pressure regulation valve. 12. The method of claim 1, wherein values of the performance quantity of the pressure regulation are ascertained in the first measuring interval and the second measuring interval both when an injector of the fuel injection system is in a new condition and when the injector is in an older condition, and the values ascertained in the first and second measuring intervals when the injector is in the older condition are compared to the values ascertained in the first and second measuring intervals when the injector was in the new condition, and the state of the pressure sensor is deduced from the comparison. 13. The method of claim 1, wherein values of the performance quantity of the pressure regulation are ascertained in the first measuring interval and the second measuring interval both when the pressure sensor of the fuel injection system is in a new condition and when the pressure sensor is in an older condition, and the values ascertained in the first and second measuring intervals when the pressure sensor is in the older condition are compared to the values ascertained in the first and second measuring intervals when the pressure sensor was in the new condition, and the state of the pressure sensor is deduced from the comparison. 14. A method for operating a fuel injection system of an internal combustion engine, the method comprising: providing pressurized fuel in a pressure storage device;regulating a fuel pressure prevailing in the pressure storage device with the aid of a pressure regulation device;during a first measuring interval, performing at least one fuel withdrawal from the pressure storage device, and during a second measuring interval, not withdrawing fuel from the pressure storage device;during the first measuring interval and the second measuring interval, ascertaining a performance quantity of the pressure regulation in each case;ascertaining, as a measurement of the fuel quantity withdrawn during the first measuring interval, a difference between the ascertained performance quantities; anddetermining that a pressure sensor is outputting pressure values that are higher than actual pressures that are being sensed and represented by the output pressure values in response to the ascertained measurement of the fuel quantity being lower than a predetermined value. 15. A method for operating a fuel injection system of an internal combustion engine, the method comprising: providing pressurized fuel in a pressure storage device;regulating a fuel pressure prevailing in the pressure storage device with the aid of a pressure regulation device;during a first measuring interval, performing at least one fuel withdrawal from the pressure storage device, and during a second measuring interval, not withdrawing fuel from the pressure storage device;during the first measuring interval and the second measuring interval, ascertaining a performance quantity of the pressure regulation in each case;ascertaining, as a measurement of the fuel quantity withdrawn during the first measuring interval, a difference between the ascertained performance quantities; anddetermining that a pressure sensor is outputting pressure values that are lower than actual pressures that are being sensed and represented by the output pressure values in response to the ascertained measurement of the fuel quantity being higher than a predetermined value. 16. A method for operating a fuel injection system of an internal combustion engine, the method comprising: providing pressurized fuel in a pressure storage device;regulating a fuel pressure prevailing in the pressure storage device with the aid of a pressure regulation device;during a first measuring interval, performing at least one fuel withdrawal from the pressure storage device, and during a second measuring interval, not withdrawing fuel from the pressure storage device;during the first measuring interval and the second measuring interval, ascertaining a performance quantity of the pressure regulation in each case;ascertaining, as a measurement of the fuel quantity withdrawn during the first measuring interval, a difference between the ascertained performance quantities; andexecuting an algorithm according to which a condition of a pressure sensor is determined, wherein the determining the condition by the execution of the algorithm includes: determining that the pressure sensor is outputting pressure values that are higher than actual pressures that are being sensed and represented by the output pressure values if the ascertained fuel quantity is lower than a predetermined value; anddetermining that the pressure sensor is outputting pressure values that are lower than actual pressures that are being sensed and represented by the output pressure values if the ascertained fuel quantity is higher than a predetermined value. 17. The method of claim 4, wherein the first and second measuring intervals are during at least one of a coasting mode and a gas exchange phase. 18. The method of claim 1, wherein the first and second measuring intervals are during periods in which the engine is operational without any injection into the internal combustion engine. 19. The method of claim 1, wherein the pressure regulations in the first and second measuring intervals include performing a control to counter any deviations from a constant pressure being maintained in the pressure storage device throughout the first and second intervals. 20. The method of claim 1, wherein the pressure regulations in the first and second measuring intervals include providing fuel to the pressure storage device in order to counter any deviations from a constant pressure being maintained in the pressure storage device throughout the first and second intervals, and the performance quantities correspond to respective meterings of fuel into the pressure storage device to counter the deviations and bring the pressure in the pressure storage device back to the constant pressure. 21. The method of claim 1, wherein the pressure regulations in the first and second measuring intervals include providing fuel to the pressure storage device in order to counter any deviations from a constant pressure being maintained in the pressure storage device throughout the first and second intervals, and the performance quantities represent respective states of a fuel metering device for metering fuel into the pressure storage device to counter the deviations and bring the pressure in the pressure storage device back to the constant pressure. 22. The method of claim 1, wherein the pressure regulations in the first and second measuring intervals include providing fuel to the pressure storage device in order to counter any deviations from a constant pressure being maintained in the pressure storage device throughout the first and second intervals, and the performance quantities represent respective states of a pressure regulation valve for countering the deviations and bringing the pressure in the pressure storage device back to the constant pressure. 23. The method of claim 1, wherein the withdrawal of the predetermined quantity of fuel is not based on the signal output by the pressure sensor and is not based on the regulating performed by the pressure regulation device.