Coolant-temperature sensor DDE 5.0/5.1

The coolant-temperature sensor is screwed into the cylinder head and registers the coolant temperature by means of its variable resistor (NTC= Negative Temperature Coefficient).

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

• Exhaust-gas recirculation
  
• Injection volume calculation
  
• Control condition for air conditioning system
  
• Activation condition for radiator shutter (only M47TU)
  
• Activation condition for electric auxiliary heater (only M47TU)
  
• Charge-air-pressure control
  
• Preheater time control
  
• Activation of electric fan
  
• Activation of swirl flaps (only M47TU and M57TU)
  
• Idle speed control
  
• Rail pressure control
  

Troubleshooting

If the coolant-temperature sensor is defective, faults 3EE0, 3EE1 ”Coolant-temperature sensor” can be stored.

Test note

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

Setpoints for resistance check

• Resistance at 20°C: 2.5 - 3.0 kOhm
  
• Resistance at 50°C: 0.7 - 0.9 kOhm
  
• Resistance at 100°C: 0.12 - 0.17 kOhm