Mass Air Flow Sensor DDE 3.0

The mass air flow sensor measures the mass of fresh air drawn in by the engine.

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

• Exhaust gas recirculation
  
• Calculating limitation volume
  

Function

The DDE control unit supplies the mass air flow sensor with voltage and ground as follows:

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

Depending on the mass of fresh air drawn in, the mass air flow sensor returns a measurement voltage via the A_HFM signal to the DDE control unit. This measurement voltage is converted into air mass with the units mg/stroke/cylinder.

Troubleshooting

Fault code 26 "mass air flow sensor" is stored if the mass air flow sensor is defective and a substitute characteristic curve is used in the DDE control unit.

Consequence:

• Exhaust gas recirculation is deactivated