Intake Air Temperature Sensors DDE 5.0

The intake air temperature sensor is integrated in the air mass meter and measures the temperature of the fresh air drawn in by the engine.

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

• Calculating smoke limitation volume
  
• EGR control
  

Function

The DDE control unit supplies the intake air temperature sensors with voltage and ground as follows:

• U_HR, battery voltage
  
• U_HFM, supply voltage 5 V
  
• M_HFM, ground
  

Depending on the air temperature, the intake air temperature sensor returns a measurement voltage via the A_TANS signal to the DDE control unit.

Troubleshooting

If the intake air temperature sensor is defective, the following faults may be stored:

• 3F70, Intake-air temperature sensor signal circuit break or short circuit to B+
  
• 3F71, Intake-air temperature sensor signal short circuit to B-
  

If the intake-air temperature sensor is defective, the DDE control unit reverts to a substitute value.