E320 1999

Engine Coolant Temperature Sensor

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Location





Click image to see an enlarged view

Fig. ECT sensor location

Operation



The ECT sensor is used to monitor the coolant temperature. The ECT sensor has a built-in thermistor with a resistance that varies according to the temperature of the engine coolant. The variations in the resistance are reflected in the voltage output from the ECT sensor.

Removal & Installation



M112 & M113 Engines
  1. Before servicing the vehicle, refer to the precautions.
  2.  
  3. Remove rear section of lower engine compartment paneling.
  4.  
  5. Open engine hood and raise to vertical position.
  6.  
  7. Reduce pressure in cooling system, to do this, slowly open the cap at expansion reservoir and reclose.
  8.  
  9. Remove air filter housing.
  10.  
  11. Release and disconnect electrical connector at crankshaft Hall sensor.
  12.  
  13. Unlatch the electrical connector at the coolant temperature sensor and disconnect.
  14.  
  15. Unscrew bolt and remove clamping plate.
  16.  
  17. Fit new O-ring to new coolant temperature sensor.
  18.  
  19. Pull coolant temperature sensor out of cylinder head and immediately insert new coolant temperature sensor.

    Click image to see an enlarged view

    Fig. ECT sensor location

  20.  

To install:

  1. Installation is the reverse of removal.
  2.  
  3. Tighten clamping plate for coolant temperature sensor to cylinder head to 6 ft. lbs. (8 Nm).
  4.  
  5. Pour in coolant and bleed cooling system.
  6.  
  7. Read out fault memory and erase if required.
  8.  

Testing



All Mercedes Benz electronic testing is performed by reading the fault memory of ME control unit and if necessary, working through test schedules contained in the Star Diagnosis tool.

 
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