Engine Coolant Temperature Sensor DDE 4.1

The temperature sensor is screwed in the water pump housing and registers the coolant temperature by means of its varistor (NTC= Negative Temperature Coefficient).

The coolant temperature serves as a measurement variable for following functions:

• Exhaust gas recirculation
  
• Injection volume calculation
  
• Limit volume calculation
  
• Start volume calculation
  
• Control condition for air conditioning system
  
• Deactivation of boost pressure control due to cold start
  
• Preheater time control
  
• Activation of electric fan
  
• Idle speed control
  
• Rail pressure control
  
• Engine mount control
  

Troubleshooting

Fault codes 0115, 0116 "coolant temperature sensor" are stored if the temperature sensor is defective.

Test note

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

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