Coolant temperature sensor DDE

The 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
  
• Limit volume calculation
  
• Start volume calculation
  
• Control condition for air conditioning system
  
• Preheater time control
  
• Activation of electric fan
  
• Idle air control
  
• Rail pressure control
  

Troubleshooting

Fault code ”Coolant temperature sensor” is stored if the temperature sensor is defective.

Test note

The temperature sensor is destroyed by a short to B+.

Set points 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