2CF8, 2CF9, 2CFA Service Engine Soon Lamp On

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N62TU Engine Wiring Harness Faulty

Vehicles Concerned

  • E70 X5
  • E60 5 Series
  • E63, 64 6 Series
  • E65, 66 7 Series


The service engine soon lamp is illuminated, also a message may appear that the engine is in fail safe mode. The DSC lamp may also be illuminated.


The faults stored in the DME are 2CF8, 2CF9, 2CFA. The faults are related to the electronic throttle valve potentiometers 1 & 2; the faults are currently not present. The integrity of the crimps in the wiring harness for the throttle valve are unsatisfactory. Usually the fault 5F77 is stored in the DSC control unit with these DME faults.


For these faults the engine wiring harness with require replacement. The complete engine wiring harness includes wiring to the transmission electrical connector. The replacement of the engine harness is reasonably straightforward. Begin by removing the engine covers, micro filter housing trays, throttle boot and air box. On some vehicles it may be necessary to lower the transmission to remove the transmission electrical connecter from between the transmission and body. Before trying to remove the electrical connector from the starter, be sure to have the battery disconnected. Loosening the two mounting bolts of the starter and removing the heat shield will aid in the removal/installation of the harness from between the engine and starter.

  • Helpful Hint – Before removing the harness, take pictures of the engine harness as it is installed on the vehicle. So when it comes time to install the new harness on the engine, the pictures will be a reference to go back to for correct harness routing and installation.
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