Fuel-temperature sensor DDE 5.0/5.1

The fuel-temperature sensor is fitted in the fuel delivery shortly before the high pressure pump and it registers the fuel temperature by means of its changeable resistor (NTC = negative temperature coefficient).

The fuel temperature serves as a measured variable for the following functions:

• Engine overheating protection
  
• Injection volume calculation
  
• Calculation of the requirement for the pre-supply pump
  
• Pressure wave correction:
  In the case of a Common Rail System with more than one injection, each injection triggers a pressure wave in the line from the rail to the injector and in the high-pressure holes of the injector. This pressure wave influences the injection rate of the subsequent injections. In order to be able to use injections with variable gaps, this influence must be minimized depending on the gap between injections, the rail pressure and the fuel temperature.
  

Troubleshooting

If the fuel-temperature sensor is defective, faults 4000, 4001 ”Fuel-temperature sensor” can be stored.

Test note

The fuel-temperature sensor is destroyed in the case of short circuit to positive.