Method and device for predicting the failure time of the pressure limiting valve of a high-pressure fuel pump of a motor vehicle

A motor vehicle control unit for predicting a failure time of a pressure limiting valve of a high-pressure fuel pump of a motor vehicle, the pressure limiting valve configured to open and discharge fuel from a high-pressure region to a low pressure-region, the motor vehicle control unit configured to perform a method comprising the steps of:

• measuring a characteristic parameter of the pressure limiting valve each time the motor vehicle has been switched off;
• determining and storing a variable determined by using the characteristic parameter measured after each time the motor vehicle has been switched off, the variable being an aggregate of at least three previously calculated variables;
• determining a time profile of the variable determined from the characteristic parameter measured after each time the motor vehicle has been switched off, wherein the time profile is tracked against the number of operating hours of the pressure limiting valve;
• predicting a future profile of the variable determined from the characteristic parameter based on the determined time profile of the pressure drop tracked against the number of operating hours of the pressure limiting valve;
• and
• comparing the predicted future profile of the variable determined from the characteristic parameter with a predetermined wear limiting value and predicting a time at which the predicted future profile of the variable determined from the characteristic parameter reaches the predetermined wear limiting value based upon the comparison.