Diagnostic Trouble Code (DTC) Information ECM-640C

Condition 

The diagnostic trouble code (DTC) is stored if the ratio between the measured boost pressure (measured value from the boost pressure sensor before the throttle) and the calculated boost pressure (calculated value after the throttle) is incorrect.

The diagnostic trouble code (DTC) can be diagnosed when the engine is running and the turbocharger (TC) control system is not active.

Substitute Value 

• Reduced boost pressure.

Possible Source 

• Air leakage downstream of the turbocharger (TC) (between the turbocharger (TC) and the electronic throttle unit)
• The boost pressure sensor has come loose (measures the atmospheric pressure)
• Damaged boost pressure sensor.
• Damaged check valve to crankcase ventilation.

Fault symptom[s] 

• Poor performance.